23+ year pool pro Matt Mueller reached out to teach about Reverse Osmosis (RO) filtration for swimming pools. It's far more fascinating than I thought. Matt talks about concepts like density stratification, biofouling and more.
[00:00] - Intro
[01:50] - Matt Mueller's Background
[08:49] - Issues that Led to Reverse Osmosis
[11:03] - Draining and Refilling Depends on Tap Water Chemistry
[12:33] - The RO Process
[17:17] - The RO Experience, from a Customer's Perspective
[21:34] - Is Dilution the Solution to Pollution?
[23:14] - Density Stratification
[29:36] - How Low Should You Go?
[34:32] - What is Osmosis?
[36:09] - Is it Drinking Water Safe?
[37:27] - Flow Rates
[39:00] - How Much Does RO Filtration Cost?
[41:19] - Biofouling
[46:06] - What Can Be Removed from Water?
[47:10] - Closing
187. Reverse Osmosis Filtration (w/ Matt Mueller)
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Eric Knight: Welcome back, everybody to the Rule Your Pool podcast. This is episode 187. I'm your host Eric Knight. And today we are talking about something that was on my list like four years ago, and I just never got an expert on here to talk about it, but I got the questions a lot when I was with Orenda. Specifically, how do you lower cyanuric acid? Or how do you reduce total dissolved solids? Or how do you reduce calcium if the calcium's too high to maintain LSI?
The answer was always, well, the easiest and cheapest way is to drain and dilute, unless you have reverse osmosis filtration, or RO. And the question would inevitably go, well, what's that? And so we did this article on it and I did my own research, but most of the sources that I had at the time were not from swimming pool reverse osmosis. It was from industrial, like drinking water, house systems, things like that. So, you know, I just tried to apply it to the pool. There was a diagram of a trailer, if I remember correctly. But it has gained a lot of popularity, especially in the era of droughts in the southwest part of the United States. I'm thinking Arizona, Southern California, anywhere with water restrictions. Draining pools is not always an option. And if it is, it's a very expensive option and you have lots of regulators about it.
So Reverse osmosis is a great solution and I wanted to talk about that for a few years. And as it happened, one of our listeners reached out through ruleyourpool@gmail.com to talk about this topic because he does operate a reverse osmosis business in Southern California. And I want to welcome him to the show right now: Matt Mueller, welcome to the Rule Your Pool podcast.
Matt Mueller: Hi Eric Thanks for having me
Eric Knight: Yeah, thanks for being on the show. Thanks for reaching out. I had a lot of questions about reverse osmosis. And you reached out with a pretty cool document summarizing it, and I look forward to getting into that today with you.
[00:01:50] Matt Mueller's Background
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Eric Knight: So let's start at the beginning. You've been in the pool industry since 2003, you said. So that's what, 23 years? How'd you get started and what led you from pool service into what you're doing now?
Matt Mueller: Yeah in high school my cousin, basically her in-laws had a pool business and they asked me to help during the summer. And so I started a lot like most people, just as ride along kind of learning the trade just from experience and doing what the owner of the company does. Then that transitioned to me working after school for them, kind of independently, so in high school I was running routes by myself. We had a pretty cool work experience program in high school so we could take the latter part of the day and work. And my wife and I got married early at 20, and so during this period she was definitely on the nurse track. I was also on the track of being a fireman, and we looked at all right what's that going to look like in the future for a family? And the scheduling looked bad.
You know, I had this, I had this thing going. Those uh, that company had sold me about 18 accounts and I had a few family and friends that I added on there. And we decided, you know what? This is a blessing, and this can work and we're not going to scorn it, basically.
Kept moving and growing a lot of word of mouth increase. So at some point I was growing enough that I needed some more help and brought on a few people here and there. But I definitely call myself an accidental entrepreneur because it was not the direction I was heading. And I'm good at the work, you know the business side of things can get hard at times. And it has proven to be really good for our family, And it's it's worked well. Yeah
Eric Knight: That's wonderful. Yeah. Well, I mean, speaking of being good at the work, nobody starts good at the work. You have to learn, and then you learn things the hard way inevitably. And, uh, I'm in the education business as you know, so like you, you can't learn expertise in a seminar. You can't learn mastery in a seminar. You have to get out there and actually do it. But you can certainly get a running start.
So where'd you start in terms of skillset and what are some of the things that you've learned? And I know that you listen to this podcast, which is great, but how, how did you start and, and where did you get to prior to getting into reverse osmosis?
Matt Mueller: Yeah I'd say I started with test strips and guesses, and that's kind of essentially how I was trained. And obviously okay there's got to be chlorine in the water and the pH has got to be balanced. There's something about alkalinity, and then CYA? Yeah that's something you add once a year and bill for. You know those are kind of like the basics, and that's not exactly right. But I was taught how to clean filters well, you know, and just by experiencing it just by looking at valves, looking at a plumbing layout, I was just able to, it made sense to me. I was able to understand how the water flowed, what the dynamics of it were. And as time went on and I was doing my own thing, starting my own business, you know there was this sense of I need to understand how this works and try to do the best I can. So, um, I Did some work for another pool pro and he used a drop kit. So I'm like well I think I should use a drop kit. So, uh, My first real introduction to the LSI was you know with a little blue booklet and a little wheel LSI calculator.
Eric Knight: I love it. Yeah.
Matt Mueller: yeah So that my eyes and started to make a lot of sense to me. And I started to think well okay so there's cyanuric acid, and that's part of the balance. And there's calcium and that's part of the balance. And then a lot of things started to make sense. Like okay why is there white scale everywhere? Why when I put in this gallon of chlorine do I see this giant cloud? And even in some cases working for the other company, like purple scale on stuff? And you know for a while that was just a mystery.
And I even remember putting in soda ash to a pool and it clouding for days. And now I know well obviously that's calcium fallout, and the calcium was really high. And so things were off, and so I now know what I was seeing. But at that point it just was a mystery. There's something to avoid right? Okay you don't do that, but why? You know So those why questions always got at me. And that always wanted to make me learn a little more So
Eric Knight: Well, that's awesome because I think a lot of people, they learn things the hard way, but they don't necessarily learn why it happened. They just learned, oh, don't do that. But I'm not sure which part of that was the one that caused the problem. So, you know, it takes a while sometimes. You have to do a lot of trial and error. And let's be honest, we're in a weekly route. You're there for 15, 20 minutes. And if you have to troubleshoot, you could be there for longer. But that backs up more work when you have a full route. So I think a lot of people just kind of hope. And a lot of the pros that I've spoken to over the years, they would just come back nervous to the pool. Just what am I going to walk into? And now with a much more predictable system, because now you, you have been following this, you have been mastering the LSI, water is a lot more predictable. Would you agree?
Matt Mueller: Yeah definitely. And I think one other like major mystery to me was like in a salt pool especially with solar, I would see white scale adhering to the horizontal surfaces of a spa especially, or say a Baja step. And just this white scaling all over. sometimes so bad that it was like sandpaper. And obviously those are detriments of mine. Now I clearly know what's driving that. Well your pH is way high, you've let the alkalinity come too high so you you don't have a lid on the pH, now you're running water through a solar system, so it's now hitting the salt cell at say a hundred degrees off the roof. And now it's going through that going through that electrolysis process and then it comes out into a spa where there's no agitation or vacuum to take care of it?
Well yeah of course it's going to adhere as scale. But yeah that was a total mystery. But now I know, Oh well clearly that has an explanation. And I was down on salt cells at that point. But I'm like no they're fantastic if you know how to manage the water because you don't have any byproducts from the chlorine it produces.
Eric Knight: Yeah. A lot of people don't realize a salt cell is actually net neutral pH. It's a 7.0 pH when it comes into your pool. Now it's not in the salt cell. It's not because you have sodium hydroxide on the cathode and you have chlorine gas on the anode. Pure acid, pure base. But that means, you know, I don't know, I'm going to guess six feet or so after the salt cell, they neutralize each other. So that's not why the pH rises. It's the turbulence as you now know.
But that's great. I love how you're, you're figuring things out and then you can go back in your past and look at what was happening and think, oh yeah, that's why.
[00:08:49] Issues that led to Reverse Osmosis
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Eric Knight: But to get to making the pivot that you did into reverse osmosis filtration, what were some of the problems that led you to that? And how did you discover it? Because you must have been facing something that was alleviated, I'm guessing, by reverse osmosis.
Matt Mueller: After the little Blue Book education I started realizing alright, if calcium stays at like 700 or 1000, really hard to manage warm water and uh, there was a, a local guy he actually pioneered a lot of our local mobile reverse osmosis. His name's Bruce Wetstein with Pure Water Industries. And so I met him I believe at probably a distributor where I was buying chems. And we built a relationship and he purified quite a few of my pools. As just a practicality thing, draining and refilling a pool as a single pole guy with a route, it's not super simple, because the setup takes a little while, where's all that water going to go? But mostly the refilling. I mean the refilling process takes well over 24 hours. When is it going to fill up? And you have to go back.
It was a burden to me. Something that I would rather avoid cause it was such a time suck. And also that liability of okay, is the water going to stop at the right point? When do I go back? So having somebody be able to do that and produce water that's better than I would've filled it with anyway was really attractive. And all I had to go back and do was start the water up.
So the way he did things was he just did the purification and then he let me know when it was done. So then I'd go back and you know the water be just the right level I'd make sure it'd have CYA, chlorinate it, and kind of get things back on track. So I was able to see all right this acts like taking care of a new pool.
Because us as pool guys we always know like okay new pools they tend to behave really good. And then after about two years, eh not so much. You know it doesn't act like it did before. So it gave it that new pool feel where you know the idea is lower chems, less algae, easier maintenance, right? And I didn't exactly know why at that point. I just knew that, okay this makes sense for my business. This makes sense for my time, and I like working with this person, and yeah and he was a great guy. Educational and it's a good relationship.
[00:11:03] Draining and Refilling Depends on Tap Water Chemistry
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Eric Knight: Yeah. Well the other thing that a lot of folks don't really think about is draining and diluting it is the most affordable thing. It's also the fastest. But it really depends on what your tap water is. So like in the northeast, they often have to truck in water. Let's say the house is on well water, and it may be loaded with copper or iron or something like that. And who know, who knows what else? And so draining and refilling in the northeast, and I've been a part of some of these projects for like drain and acid washes of old plaster finishes that they're just going to maybe polish it or acid wash that they refill. They'll bring trucks in and it could be thousands of dollars. It's not garden hoses doing that every time. Now it is usually. But that's not always the case. Because you can fill a pool from a series of trucks in under two hours as opposed to 40 hours or whatever it is. And you're right, a lot can go wrong in those 40 hours. And again, it's completely dependent on what is in the tap. What if the house has a softener? You know, there's almost no calcium in that water.
Matt Mueller: Super aggressive Yeah
Eric Knight: I remember a startup from one of our customers in Phoenix. He tested the hose and that spigot was after a softener. He is like, oh my gosh, there's only 10 parts per million calcium in this. I need to load this thing up with calcium. Yeah, but he didn't know that that one was on the softener, but the one on the side of the house wasn't on the softener. And that one had like 450 ppm, and so he way overshot on calcium. You know, but you know I would've made that same mistake too. I'm not going to test both spigots until I heard that story.
[00:12:33] The RO Process
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Eric Knight: So yeah, the, the drain refill, there's a little bit more nuance to it, whereas what you're doing with an RO trailer, and I want you to walk me through that process so that the listeners can get an idea of what they would experience. The RO trailer doesn't really care what your tap water is. It's going to take what is in the pool, filter it, and put it back in the pool. And I know there's some loss, but I'm going to let you speak to that. So you got into the game. What, when did you get your first trailer and how many have you been doing?
Matt Mueller: Yeah 2023 I was able to or late 2022 sorry No wait I don't know either way, one of those years. I was able to you know build up enough capital in my business and purchase a trailer. And so to date I've purified I think 118 pools. I haven't been super aggressive on marketing and things like that, be cause I still have my service business and I want to make sure those customers are well taken care of. And I've been doing a lot of them of course.
What we're doing is we're taking the water in the pool we're running it through an extremely fine, you could think of it as a filtration, it's not exactly correct to think of that because it's actually like molecular transfer through a membrane. So it's your pool filter is particulate filtration. So it's going to filter things that are large. You can think of reverse osmosis as a filter for total dissolved solids. So things that actually get dissolved into the solution of the water, like your TDS, your calcium, phosphates can be
Eric Knight: CYA, phosphates, Yeah.
Matt Mueller: Exactly and those are the main four that I look at. Because those are the problem childs that you can't really deal with as effectively. So that's our main
Eric Knight: Well, well, hold on, hold on, hold on, hold on. Those, those may be the main four that you look at, but there are big problems that can accumulate. I'm thinking things like nitrates, that most people don't test for. Nitrates are a pain. That's food for algae and there's no other way to get rid of them, because that's it's final oxidation state for nitrogen. So they're in there just like phosphates. Chlorine doesn't interact with them either. So nitrates. Sulfates, then you have other nitrogen compounds. Can it remove combined chlorine? I would imagine it could.
Matt Mueller: Yeah it can. So so we're talking at 10000th of a micron as
Eric Knight: Whoa.
Matt Mueller: about two microns is your best like DE filter. So you're talking about thousands of times smaller. And that's why it gets down into that granular molecular level, and you're actually pushing out water from the stream into the permeate path or the fresh water path basically. And obviously we're getting a little into the weeds probably a
Eric Knight: That's okay.
Matt Mueller: but
Eric Knight: No, no, no, no, no, no. This audience is, they're probably already asleep by now at the rate that I will operate. But we, we go deep on this show, so keep going.
Matt Mueller: Yeah it's so funny like when you, I remember an episode a little while back where you talked about ion exchange on ships and the chloride exchange. And I was like oh just feed me more I love that stuff so much but I know you talk
Eric Knight: Nerd.
Matt Mueller: people's eyes glaze over But it's just interesting like water has you know there's people that get their doctorate and how water works. And it's really intriguing, and pretty amazing. Yeah I
Eric Knight: I just had one, I just had a microbiologist on, Dr. Roy Vore two episodes ago, and he's got his doctorate and he specializes in recreational water illnesses. And he's, he's just a swimming pool focused PhD. But there are people that specialize in this and think of like the people that run SeaWorld. Think of the people that run those kind of aquariums where, you know, literally they have life in that water. They'd have to be super precise. Drinking water people. Wastewater people. Irrigation people. Water's a huge part of the world we live in, and managing it is a massively important industry. We are in a very small subset of the water industry. We are in recreational water. So, you know, we think of our industry as being, because it's all we know. I used to think swimming was a really big deal because I was in it. And then you realize, wow, swimming is tiny. I had no idea just how small it is when you compare it to football or golf or tennis or something like that. It's, it's a very, very tiny sport. But I get what you're saying. So sorry to, to derail you. I just went off on a tangent. I do that. So anyway, you were saying?
Matt Mueller: We'll just we'll review the we'll review the RO process kind of in a nutshell.
Eric Knight: I want the audience to know for a moment that Matt is the first guest that I've ever had on this show that made his own show notes. Eat your heart out, Jarred. Not that you would ever read these, but he's got show notes he's reading off. He came prepared. That's awesome. Guests in the future come prepared. This has been marvelous so far.
Matt Mueller: I did have some time on a flight back from my anniversary trip with my wife, so I spent that time well. Wrote some stuff on the plane.
Eric Knight: Nice.
[00:17:17] The RO Experience, from a Customer's Perspective
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Matt Mueller: So in in a nutshell, what it looks like to the customer or the pool pro, I have a it's a 20 foot enclosed trailer that houses an industrial RO system. It's self-powered by a diesel generator. And so it it's kinda like what we're talking about. I'm bringing the water reclamation side of water to the pool side. So it's like what you'd see at a desal plant on much smaller scale, but it is an RO system that uses the same membranes that a desal plant or your water reclamation plant would use. Smaller scale, but it's still large scale compared to your under the sink RO system. But they all conceptually work the same.
And what it looks like for the customer is I park the trailer, and I run a suction hose from the trailer to the pool So I set a depth, and have my suction hose there. And then I return the pure water to the top of the pool. So two hoses are running to and from the trailer to the pool. And then I have
Eric Knight: Are these like, you know, one inch hoses? Inch and a half? Okay.
Matt Mueller: inch and a half flex. Any bigger, the hose gets pretty cumbersome. And also the flow rate on my system it wouldn't really benefit from larger hose.
Eric Knight: So, so basically, basically like a vacuum hose. That's an inch and a half.
Matt Mueller: Yeah. Yep that's a good example. And I have lots of length, so I can bridge some pretty long distances, about up to 200 feet. And I haven't had any trouble accommodating people's pools. And I live in a pretty rural area, so I've definitely had some longer runs and different things. So but if you're in a neighborhood it's real easy. And then I use two garden size hoses. One for the waste, because RO does produce some waste, but it's minimal compared to draining and dumping all of it. So one of those we find either your sewer clean out or some other appropriate area to drain off the waste. And that's non chlorinated, but it is it's called brine water. So it's got a lot of salts in it, It's got a lot of calcium in it. So we we don't discharge that to areas with grass or plants because you know it's that sense it's not good for those. Go ahead
Eric Knight: Do you have to get a permit? Because I know in California certain areas you need a permit to put salt water down, or pool water down a sewer. Or I don't even know where you're supposed to waste it. Honestly, I've never lived in California.
Matt Mueller: Yeah my research in our area is that it needs to be non chlorinated. So we can discharge non chlorinated water either in in any kind of drain or sewer. It's the chlorine they worry about cause I think it interacts with like sewer gases basically.
Eric Knight: Oh, okay.
Matt Mueller: problems. They handle all kinds of other solids and things like that. So really, if you think about putting it in a sewer clean out it's going to it's going to link up with lots of other water flow. And that dilution, you know maybe it is say 4,000 parts per million calcium going into it. Well that's going to dilute really quickly into the sewer flow almost to a negligible amount just because, we can get into some numbers of how much waste I produce, but it's generally going to be 20 to like 15 percent of the pool water. Several thousand gallons with that concentration into the overall water system is a pretty minor dilution when you actually look at it mathematically.
Eric Knight: Sure.
Matt Mueller: and then in case in cases where customers are on septic, we look for the natural drainage area and utilize that. And generally the ground is absorbing that. And that's also generally fine because when you get dilution from rain and things like that, it's going to spread out those contaminants just like any other system like that. So
Eric Knight: Gotcha. So you're saving roughly, you know, 85 to 90% of the water that would otherwise have been drained?
Matt Mueller: So our our kinda lower side of things, it's like a really heavily saturated pool, lots of salt, lots of calcium. Numbers 1200 parts per million calcium, numbers like 5500 TDS. Sometimes we'll be down at like 67%. I think 65 is the absolute worst percentage water retention that I've had. And then the best, it can get up to 90, say if we're doing like somebody who's just looking to do good maintenance on their pool, it's been pretty well kept. We can have really high water retention too. So it just depends on how much we need to dilute and how much we need to get rid of.
[00:21:34] Is Dilution the Solution to Pollution?
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Eric Knight: Gotcha. Sorry to interrupt you. You were saying they say the the solution to pollution is dilution.
Matt Mueller: Exactly That's a common well trodden phrase and it is true, so yeah.
Eric Knight: That's awesome.
Matt Mueller: That covers the waste one. And because we are producing waste, at the same time we'll hook up to a garden hose spigot, and then that will feed back into the trailer. So both of these flow rates are metered. And so the reason for that is we don't want to expose any of the customer's plaster to any sun or drying out. Because I think maybe on the first episode of the new podcast you talked about how concrete is really good in compression but not good in expansion. So one of our big things is to minimize any sun exposure to surfaces. I've seen especially on on old plaster pools if you take the water weight out, in like two weeks or so you get all these chips because the bond isn't strong anymore. And so that becomes a problem. So anyway so we meter the water going out we match it with what's coming in so the water level's completely stable the whole time.
And oftentimes these are the numbers that we shoot for and end at: usually 150 to a hundred 170 parts per million calcium, 500 to 700 TDS, zero to 25 CYA, and generally under a hundred parts per billion phosphate, depending on where it starts. Now the machine absolutely has potential to go less than this, but that just becomes a waste of water and time. It could go extremely low. Like you could go down to 10 parts per million calcium, you could go to 200 TDS, but what for? You know, at that point it's a waste of water and you just have to add it back because it will be so aggressive.
[00:23:14] Density Stratification
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Eric Knight: Right, because at that point you're going too far. And furthermore, this is not a single pass. Because water doesn't wait in line to go into your suction hose. So it's a dilution. It basically, you calculate and you're doing this?
Matt Mueller: That favorite part of the whole thing is this concept called density stratification. I didn't know it was called that until I looked it up. But it was so interesting to me when I first got the machine. What happens is, you can take high TDS water, which is essentially heavier in molecular weight than low TDS water. And if you gently push the lighter water back onto it it will actually separate into different density layers. So so the way that our return is designed, it's an inch and a half coming in but then it spreads out into four like covered drains. You know with the correct like VGB compliant cover? And so it gently pushes the lighter water back onto the surface.
And what happens is it actually layers itself on the way down. So the way I get to calculate and save the most water, is I'll run dilution ratios at the beginning to figure out okay where do I need to set my suction depth to to hit the exact ratios I want to make this water hit the you know your 150, your 500 TDS? How do I get to those numbers? It's some mathematics and dilution ratio.
And you know at first I was like ah does that really work? And I found my favorite tool is actually a very humble one. It's a 10 foot stick of half inch PVC that I have magic marker marked with the depth sounding. So I have one to 10 feet on it so I can measure pool depths. But the way I use it, is I will slice through all the layers of water and then I'll cap it with my thumb, and so I can take a sample that includes all my different density layers which gives me an idea of what my total dilution is, and then I'll mix it.
But the fun part is that if I take a sample just strictly below my drain, so say I cap my pipe and I go all the way down and take a sample below my suction? It's like I never touched it And then if I take a sample six inches above my suction it's very pure. So it's like a saltwater freshwater cave, if you've ever seen that episode on Planet Earth, where it it separates and there's like a divide between the saltwater and the freshwater?
Eric Knight: I haven't, but it makes sense. Like you're seeing stratification.
Matt Mueller: Yes
Eric Knight: Wow. I didn't know that.
Matt Mueller: We actually encourage it with the way that our return is set up. So it gently brings the water in. And then the other factor is
Eric Knight: No way, dude.
Matt Mueller: Yeah it's fun we turn off the customer's equipment so that we can leverage that stratification to basically stop at the right point. So our machine has TDS sensors, and that's our like shutoff point is a set TDS. And so that stratification works because basically you can think of the pool water as like dropping, dropping, dropping. Like the lower TDS gets closer and closer to my suction, and then as soon as it hits the suction then the system picks it up, it shuts down.
Eric Knight: So you don't have this sitting on the main drain. You have it somehow raised a little bit above it?
Matt Mueller: Yeah So I I made like a telescoping suction. It's basically an inch and a half pipe inside of a two inch and I can set it to where I want. So this was something I kind of created on my own. I know a lot of operators, especially like in Arizona where the the evaporation is so high that they concentrate their water.
Eric Knight: Oh, so fast. It's crazy.
Matt Mueller: So so for them it's, and CYA is their biggest fight out there. So for a lot of those operators, they do just put it right on the drain because they need to take all the water out to deal with the CYA. But for me, I have a little more flexibility. Because our main issue here in SoCal is going to be calcium. We have calcium out of the tap that's about anywhere from 150 to 200. So it's pretty high. And then our phosphates is the other issue out of the tap we have
Eric Knight: well high for tap water, yes, but high for maintenance? No. But when you are losing that much water to evaporation, the calcium accumulates because it doesn't evaporate. So over time, yes, I can see your calcium getting out of line. But people always asked us like, well, what should the calcium be? Like what's the ideal calcium for my pool? And the answer is, whatever allows you to maintain LSI balance year round in your climate. Based on how you manage that pool. So it's a little bit different for each person.
But I got to go back, man. I did not know that about RO. I did not know that it stratifies. When you say that, it makes perfect sense. Here I am teaching physics on this podcast all the time. It never occurred to me that purified RO water is lighter than dense TDS water. It makes perfect sense now that you say that. And I kind of feel like a moron. But that's super creative, man. That really is. So you, you just know when it gets down and it hits that suction, your TDS meter recognizes, oh, there's a sudden drop of TDS. We did it. So it just shuts off at that point or what?
Matt Mueller: Yeah So I my machine it's really sophisticated, and like I said, Bruce Wettstein pure Water Industries, he really built a great product. It's well thought out. My brothers and I we modified it a little bit cause I didn't have like internet capability. And so we we added a system. One of my brothers is the IT guy The other one works for like big buildings and incorporating like HVAC stuff. So between the three of us, we figured out what to do, and so we automated the drive into it. My other brother helped with the networking, so now I'm able to see what's going on with the trailer when I'm offsite.
And so the run speed's pretty linear. But then for about the last maybe 5%, it starts to pick up that mixing water where we get into some different stratification, and then the pump speed is able to increase because there's less osmotic pressure. And so I can increase my pump speed to maintain vessel pressure. So that's when I know, okay I'm about done here. We're picking up lighter water, We're about to finish the process. So so
Eric Knight: That is
Matt Mueller: My cue that
Eric Knight: crazy, Matt. That's absolutely crazy now. But you say that it makes sense. But I did not realize it was that sophisticated. Honestly, I thought people just ran it 24 hours because why not? Just keep it going. But you're actually targeting a very specific finish line.
[00:29:36] How Low Should You Go?
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Matt Mueller: Yeah So when I take my tests, I like to see okay what's the customer's main problem? Is it CYA? Is it phosphates? Is it calcium? Is it a combination of? And generally when I target whatever the biggest problem is, I'll run the dilution ratio for that and the others will fall in line basically. Because the RO process is not specific. I can't specifically target something to take out, but I can dilute for what I want to get rid of. And so the other things will generally fall in line. So for example, say the CYA is really high and then the calcium's probably high too because usually they go hand in hand.
Like if the water hasn't been looked at or maintained, it's usually both, right? But if CYA is the problem, then I'll run the dilution ratio for that. And say for example I need to purify 90% of the water to hit the target number I want. Then I've got a 90% dilution ratio on calcium, and that's usually going to get me where I want too.
So I usually just pick whatever the main problem is, dilute for that, the others will fall in line too. And then I'll be able to correct what I need when I do my restart. So So yeah that's that part of it I'll say for me I've definitely just as my own curiosity and my want to understand things I've definitely taken it further than most people do. But I'm able to see all right this will save water, this will save runtime on my machine, It'll save money and chemicals, and it's just better in that sense. So that's kind of why I do it, but there's also nothing wrong with just purifying the water really well, and then kind of restarting it to the parameters you need.
And then as my pool person background, I also decided when I started doing this I want to make the process seamless for other pool pros or homeowners. Like when I'm done with it, I want the water to be chlorinated, I want it to be LSI balanced. So my thing is I'll come help you out and in 24 hours you're ready to go again. Like when I leave, you can swim. And in fact you can swim while the process is going on. It is the only time you get the holy grail of no chemical swim, right? This is a non chlorinated bottled water swim while it's going on. And we cover all of our suctions with VGB compliant drains. We've got no electrical cords going into the system, so yeah you actually have that opportunity to have that once once-in-a-lifetime, or in my case once every couple years swim.
Eric Knight: So let's talk about what you do to the water. So you, you bring these hoses in, there's no electrical components at the pool. It's hose in, hose out. So you take a sample of the water.
Matt Mueller: I do start it with a sump pump. To be clear, there's an electrical cord for about 20 minutes of the process and then that sump pump comes out, because I need to prime my line.
Eric Knight: Gotcha. Okay. So other than that though, like when you're not there, there's nothing that the homeowner could get shocked from? Okay. So let's talk about what you do to the water. Obviously you test it, and then you determine the dilution ratio, which determines the depth of your suction, which I think is brilliant.
What do you have to do to the water prior to starting this process? And the reason I ask is you said unchlorinated water that you're wasting. So do you de-chlorinate the pool or does the natural process de-chlorinate it?
Matt Mueller: I do have to de-chlorinate, so that's actually I usually park the trailer, and then the very first thing I do is I'll test the chlorine in the water. And I use sodium metabisulfite to neutralize chlorine. It's a very fast chlorine neutralizer. And so in about 20 to 30 minutes I'll have it at zero. And the reason for that is because the membrane is made out of it's called polyamide, and it's extremely susceptible to chlorine damage. So if I don't neutralize the chlorine, I will suffer damage on my membranes and they won't they won't purify as well. Basically you'll lose a lot of ability to purify.
Eric Knight: You know, I've never heard of sodium metabisulfite. I've heard of sodium thiosulfate. And I know that's used in a lot of commercial pools. And actually kind of a crude way of very quickly de-chlorinating a pool is to purge with SC-1000, because chlorine will attack it and lose, and it doesn't have time to like bind everything. But I'm not sure what SC 1000 would do to your membrane either. But I'm sure chelated metals would get picked out if you're, I mean, you're at one 10000th of a micron. For context here, if your DE filter does two microns, and your cartridge filter does, I think it's like 8 to 12? depending on the manufacturer. And then you've got sand filters that's like 20 something, 24, 28, something like that, microns. Meaning the size of particle that it can capture. So sand doesn't have nearly the screening capability of DE. But let's just go with DE at two microns. That's 20,000 times more screening ability. Meaning you can capture something 20,000 times smaller than the DE filter can.
That's absolutely incredible. But it's, it's not physical filtration, right? It's ions, like you said, it's, it's actually sending atoms through a membrane, right?
[00:34:32] What is Osmosis?
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Matt Mueller: The process of osmosis is water passing through a membrane moving from either a low concentration gradient to a higher concentration gradient. And it will overcome a pressure barrier to do so. And so it's not only a pressure type of operation, but it's a chemistry operation, right? In osmosis you're taking a lighter gradient water or a more pure gradient water and it will want to bind with the high concentration, and it will overcome pressure to do it. So if you've ever seen some of those diagrams there's like a horseshoe tube, right? And then right in the center there's a membrane. And you have you start with equal water but this is like say lower TDS, this is higher. It will actually on its own go through the membrane and then this part of the beaker will rise on the high concentration side. So that's osmosis.
What I'm doing is, I am reversing that process by use of pressure, so I'm pushing that water back through the membrane so that we can get the pure back out of it and reject the the TDS out of it. So that's the opposite.
Eric Knight: Gotcha. That's incredible. You know, I've, you hear reverse osmosis. I just figured you're running through some type of filter. But yeah, it's actually going across a really fine membrane. And then pure H2O goes through that membrane.
Matt Mueller: It's not perfect but it's close. So so in my trailer, the lowest I've ever seen is 18 TDS. So I mean that's darn well close to to what's the word um, no
Eric Knight: distilled water?
[00:36:09] Is it Drinking Water Safe?
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Matt Mueller: Distilled, that's it. And so my family and I, we I'll pull water off the trailer and drink it. I'll put it into five gallon jugs. Because that's really what it is. It's a drinking water system. So as it enters my trailer, it goes through a UV purifier, a two micron bag filter, a booster pump, then into the high pressure pump. And then that's when it it's running at about 200 PSI into the what's called the vessels or the filters that house the membranes. And then that pressure is what's working in there.
And again, conceptually it's simple. They look more or less like a cartridge and a cartridge filter, except they're, rather than being accordions, they're wound in a spiral. And the pure water works its way to the center and then I have for that. And then the wastewater gets looped back around, a quarter of it gets lost and that's where the waste comes in. Three quarters of it gets looped back around for multiple passes. And so that's how we overcome the general inefficiency of RO by making it what's called a two stage multipass system. So that's technically what my RO system is.
And in other RO applications, there's three stage multipass systems, but you get into some pretty tricky chemistry at the end of those. So but that's really in the weeds but Yeah.
[00:37:27] Flow Rates
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Eric Knight: Well, no, I, I, that's what this podcast is for. I don't know of other podcasts that go into the weeds, like Rule Your Pool. So thank you for that. Now you got me wondering if it's a two pass system, obviously there's a lot more that you're pulling out. What is your, sorry. Yeah. Two stage system. What is your flow rate that you can get through this? Because it sounds like a regular pool filter you can move water, you know, 40, 50 gallons per minute. What are you getting in these trailers?
Matt Mueller: So very dependent on TDS, because that drives osmotic pressure. But commonly can get as high as about 40. That's like really low TDS water, say like 1500, and I'm just trying to reduce some CYA or calcium that's slightly elevated. I think of that as like your typical oil change. So people who are really conscious and taking good care, which I love and that's what I encourage. Because if you're doing your typical oil change on your pool water, that's when you're going to have the best results.
But I get a lot that are, okay the pool store said that this is really bad. And so I'll get calcium in the thousands sometimes, I'll get TDS that's in the six thousands. And in those cases, I tend to look at about 18 gallons a minute. The run times increase is basically what happens. But in in general, we can purify most size pools, so say 10,000 up to like 35,000. Even at those high numbers, the runtime is usually less than 24 hours in your smaller stuff and good starting point purity a lot of times our runtimes are eight to 12 to 14 hours. So that that gives a good idea.
[00:39:00] How Much Does RO Filtration Cost?
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Matt Mueller: And if people you know people are interested in cost-wise? Every operator has different prices but for me a lot of my stuff ranges from about $700 up to about $1500 for your bigger like 40 and 50,000 gallon pools. And so it is going to be more expensive than draining and refilling. But we do offer, it's fast, there's no downtime, and you don't have any risk to your surface. I do think there's some good built-in insurance there and we do provide a better product than you'd get from draining and refilling. A lot less headache it's pretty seamless so.
Eric Knight: Well you wouldn't have risk. You would have risk if you didn't balance it as soon as it's done, because you're getting it lSI balanced. If you just walked away after you RO'd it, that water's very LSI aggressive because it has almost nothing in it.
Matt Mueller: correct
Eric Knight: So you, you're doing the, the full experience for the customers. Not just the physical RO. You're actually treating it to get it back to where it needs to be.
Matt Mueller: And if it's a salt pool, I do offer putting the salt back too. But I also let that be if they wanted to buy it or their pool pro wants to do it. Then I do offer that too. And and then I give a before and after report, So it'll have their starting and ending chemistry parameters. It'll have their water waste graph, so how much water was wasted? How much was conserved? I'll do like what I did on post purification, So it tells them what their LSI balance is.
I'm connecting with the Pool pro often, and letting them know what I'm up to. If there's any chance for education I usually always share the app with the customer with the pool Pro, and say you know has really changed my business. Like using PR 10,000 weekly, using enzymes, and so I just kind of try to educate as much as I can. There's some customers it's pretty fun, they're usually engineers but they're usually like really into it. So I'm able to talk kind of on this level with them. And that's really fun. And some people are just thinking oh I just want my pool taken care of, and that's totally fine too. So I always try to make sure I'm not like fire hosing anybody with information but I do want people to have a better handle on what's going on after I left than before.
And I always leave myself open to you know give me a call, I'm your resource, I'm open to answer questions. And you know I just want to build that good relationship with pool pros and homeowners.
[00:41:19] Biofouling
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Eric Knight: That's amazing. I got to tell you. It's so much more in depth than I thought. And one of the things that he was a RO operator, I believe in Phoenix. Years ago. I don't remember his name. He's probably in my phone. But he was buying our enzyme because he was saying that the oils were jamming up the RO membrane. And so he would purge the pool ahead of time with enzyme where he would give it to the homeowner or the, or the pro who was referring him, and just make sure you get all the oils out ahead of time. Have you noticed anything regarding that improving performance or anything like that?
Matt Mueller: So I don't, um, I haven't but I could definitely see how it could work. So there is something in RO called Biofouling. And this is a good consideration of limits too. Like what I can do and what I can't. Biofouling would be from oils, it'd be from algae. Because the let's call it pores in the membrane are so small, they are susceptible to fouling from different things. And oils, organics are definitely one of them. It would be really helpful. I haven't come across too many that I've needed it on, but I also I can't take a green pool and run it through my system and have it perfect. I suppose I could but I wouldn't get very far and it would clog up. So so what I can do, my limits are, if I can see the drain and there's no active algae? So say it's say maybe you've done like an Orenda bomb on it, and it's starting to really come around we're filtering stuff out, there's nothing active anymore. Still little cloudy, but we can see the main drain, I can take over from there. But I can't just put my stuff in a swamp and clarify it. It would take a much more robust system that I don't have to be able to do that
Eric Knight: It would clog it up.
Matt Mueller: backing. Yeah exactly So so those are that's kind of my limit there. But if I did come across something that was looked really oily, yeah I would certainly consider that. I also have it's an injection tank on my system, and it injects anti scalant into the system to prevent basically calcium carbonate scaling at the membrane surface. And so yeah in other RO applications there's other injections that can be done and I'm betting that oils and enzymes are something that could be looked at.
Eric Knight: So you would need to get the physical stuff out, basically. Because you can take the dissolved particles in TDS, but you can't get algae, the slime that protects algae, biofilms, things like that? That makes perfect sense. Oils, sunscreen, lotions. We talk about it all the time on this podcast. That's fascinating. And I remember him talking about that and I'm like, I don't know how RO works really. But it makes perfect sense, because if you've ever cleaned a cartridge filter, listeners, and it's sticky, well that's because it was oils and organics that were starting to get oxidized by chlorine. And I'll give you an example.
When you feel oils. They're slippery, they're slimy, they're not sticky. But when chlorine starts to oxidize them, it doesn't have the concentration to break the carbon bonds. It, it can, if you were in like really high concentration, but in the levels we use in pools, you're not there. So instead it starts to attack these oils and they get tacky, like really sticky. And that's what you feel on the scum line. You feel it on the inside of the skimmer throat and that's what you get on your cartridge filters at the top of your sand filters. You can get it in your DE, although when you clean DE you've already back washed most of that stuff out. That makes perfect sense why that would jam up an RO filter, based on the description that you gave.
You're going through a spiral of membranes. Yeah. If you've got glue, glue is not going to go through there. Because that's a physical. It's not dissolved, it's a physical contaminant. You did say you have the pre-filter, but that would get jammed up so fast, especially if the pool is green.
Matt Mueller: Yeah exactly So so that that's our limit. But you know we can do good work with, it just has to be pretreated. But if it's still cloudy you know it kinda has that gray where you're not quite fully fixed from your swamp yet? It's kind of gray, you can see the drain? We can take that and in in the next day it'll be perfect. Like all that stuff will be gone, so
Eric Knight: You know, it reminds me. Yeah, it is. Yeah. It reminds me of this customer of, of ours at Watershape, he's one of our IWI's, who can go into a commercial pool. And instead of doing RO, he has an ozone trailer. And he's like, just give me, give me 24 hours. And he'll run hoses in and hoses out. And he will treat that pool overnight with ozone and just kill everything. And it just turns it into drinking water clear. But of course it doesn't get rid of anything. It just gets rid of pathogens and things that it can destroy. It doesn't change the TDS, it doesn't change the calcium. So it's kind of an opposite, but very similar customer experience. You're actually subtracting things.
Matt Mueller: That's cool
Eric Knight: Maybe you could Yeah, I, I would think you could ozonate the water going back in. I would think that would make a lot of sense.
[00:46:06] What Can be Removed From Water?
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Matt Mueller: I have a UV purifier on mine, so that helps with our micro contaminants and bacteria and viruses and stuff. But real quick I'll go over some of the dissolved solid micro contaminants that we can be removed from water. This is just a short list, mostly geared toward pool stuff. But calcium we've talked about, CYA, salts, and TDS, borates, phosphates. We can take out metals, copper, iron, manganese, nitrates, sulfates, silica, ammonia and nitrogen compounds, so I think that's we were talking about combined chlorine
Eric Knight: Yeah,
Matt Mueller: So it can reject those. It does take down alkalinity cause that's carbon based and
Eric Knight: It's carbonate based. Carbonate based. Yeah.
Matt Mueller: See I still have more to learn.
Eric Knight: No problem.
Matt Mueller: Detergents, residues, and some disinfection byproducts like chloramines. And then I think there was something else which I need to research more with like a three letter acronym like a precursor to some other byproducts. So it is that's kind of like your pool concentrated list but it does remove
[00:47:10] Closing
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Eric Knight: That's a lot. That's a lot. Matt Mueller, I greatly appreciate you being on here. Is there anything actually, what's the name of your company?
Matt Mueller: Yeah so my company name is California Pool Company Reverse Osmosis, or California Pool Company for short . You can find me at CaliforniaPoolCo.com. My Instagram is @calpoolco. Facebook is California Pool Co, And my personal email is matt@californiapoolco.com
Eric Knight: Be careful putting your personal email on here, man. You're going to get lots of people telling you how much they want Jarred back on the show.
Matt Mueller: And then where I know of providers working, we've got a lot around Arizona, Southern California, East Bay, the northern LA area, Ventura. Texas, so Midland, Austin, Dallas, a lot of your big places there. In Utah, St George. And I believe there's a good amount in Florida I just don't know of them. So I'm part of like a just a small group. You know it's pretty tight, so anyway those are if you're in those areas and you're interested in the process, probably just search like pool reverse osmosis, or pool water purification. And you can find a provider in your area hopefully. And if you're in the SoCal area please give me a call I'd love to be a resource if you're a pool pro or a homeowner and help make your pool just fantastic.
Eric Knight: That is so awesome. That is adding quality by subtracting contaminants. So addition by subtraction. That's kind of like the Orenda philosophy. We want to take complexity out of the water. This mechanically does it and it does it very well. And it answers that big question that we got so much. How do I reduce CYA?
And I would always say, well, first, dial back on the trichlor. Use it responsibly, not as your primary chlorine, because that's usually the reason you have too much. And then second, you can drain and dilute or you can reverse osmosis. Now I have a lot more confidence in it. Thank you for being on the show.
Hopefully all the listeners now have a lot more confidence in it as well. And you, you now have his contact information, listeners. So if you want to learn more, Google reverse osmosis, look up California Pool Co. And Matt Mueller. Thank you so much for adding value to the listeners on, I believe this is episode 187 of this silly podcast of mine. First time you have long time listener. First time caller of what's your impression so far?
Matt Mueller: It's been great I really do thank you for the podcast information and the app because in my business it it has made a huge difference
Eric Knight: good.
Matt Mueller: I'd say about two years ago I decided to you know what? I'm going to do this Orenda thing like full. I'm going to I'm going to treat my pools weekly with phosphate remover and try to keep everything low. And it really has revolutionized stuff. I mean I keep a 55 gallon drum of enzyme and phosphate and we treat it, And so to the listeners out there I mean in it it's good science and it really matters. And so it's helped a lot and it's been fun being on and I do thank you for the value that you've given to my business and just the the willingness to share information, to teach. I really latched onto that and I try to share that myself and my own business and just to teach and share. And I do share the resources with anybody that is interested to know more, because I think they're very accessible and helpful. So I do thank you a lot.
Eric Knight: I appreciate the kind words. Thank you so much. I'm happy to do it. This show will continue. We will continue to have experts on. Matt, you are certainly an expert, and thank you again for reaching out. This is a great topic, and I get to cross that one off the list that I had, like 30 to 40 that I just never got to.
And
Matt Mueller: Yeah
Eric Knight: yeah, I'm whittling away at them at, at the speed of smell, but I'm, I'm getting, I'm getting through it, so I greatly appreciate you being on here. Yeah. What was that?
Matt Mueller: my
Eric Knight: Yeah.
Matt Mueller: of I said it sounds like my list of business things that I need to do that I need to whittle away at, find out profit margin et cetera et cetera
Eric Knight: all that stuff, man. I've got 118 tabs open at any given time with Watershape, so I've got plenty to do myself as well. But this has been great and listeners, if you have any questions or you want to reach out to Matt, you can. And if you want to reach out to me if you have any questions, it's ruleyourpool@gmail.com.
And in the next few episodes, I've got a few more guests, but I'm going to start weaving in the water chemistry class, kind of like I did a few episodes ago. I gave you like a five minute snippet of it. Well, that class is now online, so the eight hour chemistry class service 2211 essential water chemistry is now on Watershape.org.
You can go to the website, go to education, you can find it on there, you can take it now. And so far we've had quite a few people do that, and it's been great. So if you want to get that education right here and now, you don't need to wait till the next show, it's available, go ahead and sign up for that on our website.
And I greatly appreciate you listening to this podcast, Matt. Thanks again.
Matt Mueller: Thank you
Eric Knight: All right. Take care everybody.