Trying to decide on method of chlorination for prospective new build

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JamieP

JamieP

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Platinum Supporter
May 16, 2011
1,180
TX (~30 miles south of Dallas)
Pool Size
28000
Surface
Plaster
SWG Type
Pentair Intellichlor IC-60
We are planning on putting in a pretty big pool (~40,000 gallons) and I'm now second guessing my decision to do the stenner pump. I had originally wanted a SWG because of the feel of the water and the automation, but a PB scared me off of it by saying that it drives up the ph and I'd be adding acid all the time.

Our pool will not have any of the normal factors that would preclude a SWG. We'll be doing precast concrete coping and concrete decking, with no rock anywhere, so that's not the issue. I guess I'm scared of the acid comment. I'm even considering a stenner pump for acid, but that's a different issue!

There is also the consideration of the pool size, and finding the right size SWG that wouldn't be maxed out, as I've heard it recommended to 1.5-2x the size of the salt cell. Conversely, even with a stenner pump and a container for the bleach, how much bleach am I going to have to be buying to chlorinate this size pool? Which seems to be the more convenient way to go?

Does anyone have any thoughts or recommendations for my situation? I don't have a test kit yet but plan to get one to keep the pool once we build it. Would it help to know what my tap water's TA is ahead of time in order to make a better decision about controlling ph with a SWG? It's all still kind of Greek to me, but I thought I read something about that correlation.

Thanks for your help...I need it! :confused:
 
I would certainly still recommend a SWG. pH rise can be controlled through managing a lower TA level such as 70 ppm or even down to 50 or 60. You're right on finding the right cell for such a large pool but there is at least one SWG cell out there that's rated for up to 60K gallons, Pentair IC60. There may be others, but that's the one I can think of off hand. Your tap water TA is helpful to know where you will start and what kind of effect it will have when you have to do periodic refilling but that can all be managed.

A stenner pump is also certainly a good option as well but you may not get much support or proper installation from a builder unless they have done them for other builds before.
 
I am piecing together a Stenner setup for my 40k pool.
Are you planning any water features? I know you are not doing any rock.
Any water feature will do two things; drive up pH and help cool the water in summer if run at night.
So what I'm saying is, you don't avoid adding acid by avoiding SWG.

My bleach consumption (11%) ranges from 20-100oz per day.
100oz on really hot days with lots of swimmer load.
20oz when it is cool and overcast and no-one is swimming.

I add 12oz Muriatic acid every 3 days.

I buy my bleach in bulk from a local chemical supplier.

Back to the SWG, there will be times where it does not keep up or you need to SLAM.
That is when you are going to be pulling out the bleach bottles regardless.
 
JamieP,

The largest contributor to your pool's pH rise, at least in the first season, is going to be the plaster. As others have mentioned, you're not going to get away from acid additions by not having an SWG. And, as others have said, it easy to manage pH especially if you keep your TA low and use borates as a secondary pH buffer.

It sounds like your PB is trying to scare you away from an SWG with gibberish which calls into question his motives.

An IC-60 or T-15 cell is about your only choice for a pool your size.


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Thank you for your tips! I guess I should put aside my concerns about ph rise and acid additions and try to make a level comparison between the convenience of a SWG vs a Stenner setup. I don't think I would necessarily mind buying the bleach, (although time would tell!) but I don't relish having tons of empty bottles of chlorine to dispose of, since so far I haven't found a bulk supplier in my area. It sounds like I should revisit the SWG idea.

Ozdiver, the only water features that we will have will be two bubblers and a slide (which aren't even water features, I know.) To cool the pool in the summer I might rig up one of those PVC fountains, and I had read of the correlation between the aeration and ph rise. I'll just have to get more familiar with how it all works together so it doesn't intimate me so much.

Another concern I had with a SWG was the effect of salt on the trees in my yard near the pool. I was going to go with a cartridge filter to avoid water loss and chemical loss through back washing, so maybe that makes it not a big deal. Unless we get tired of them being around and end Up cutting them down, we have a couple of red oaks and chinquapin oaks in the vicinity of the pool to think about.
 
I won't make the blanket statement that pool water is harmless to landscaping because there are certain grasses and perennials that are sensitive to salt BUT, (1) the salt levels present in backwash waters are fairly low and (2) many types of landscape vegetation are resistant to sodic soils. It wouldn't take more than a single phone call to a local nursery or Ag School extension to find out if you know what types of trees you have around. There's even lots of information online regarding plants and salt-resistance.


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So, for 40,000 gallons it takes roughly 180oz (1.4 gallons) of 8.25% bleach to raise the FC by 3ppm. Standard FC loss on a hot sunny day during the heavy swim months is easily 2-3ppm/day. So your Stenner would have to deliver 1.4 gal in whatever your pump run time is for that day.

By comparison, an IC60 can deliver up to 2lbs of chlorine gas in 24 hours which would raise the FC by 6ppm.

So you can see from that limited analysis that an IC60 probably makes more sense than a Stenner at least in terms of ease.

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Thanks, Matt! That's exactly the kind of analysis I need, but that my limited understanding of pool chemistry at the moment is not capable of. It seems like a SWG is getting more and more attractive! I have an email in to my arborist to see what he has to say about the salt's effect on my trees. Thanks for making the suggestion that I check on that with someone who would know.
 
MA additions are just like pouring your morning OJ once you get used to it. Really. Been doing it for here for three years. My pool uses about 1/2 gallon of MA every 6 days. No measuring, I just estimate 1/2 gallon. Then finish off the gallon next time.

Borates don't make you add less MA, you just add twice as much half as often (roughly).

I only did borates one year. In a cold climate you lose a lot of it while lowering for winter and pumping out during the winter.

So just say roughly a gallon of MA a week (your pool is bigger than mine and it's hotter there) or many gallons of bleach each week...forever. No brainer to me without salt sensitive coping/decking.
 

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Autopilot also makes SWCG cells rated for larger pools (rated up to 67,000 gal).

I've been using a SWCG since 2004. Since adding borates and lowering TA (70-80 seems to be the sweet spot for our pool) I haven't added a drop of acid in over 3 years; pH stays at 7.5 all season.
 
Saturn94 said:
I've been using a SWCG since 2004. Since adding borates and lowering TA (70-80 seems to be the sweet spot for our pool) I haven't added a drop of acid in over 3 years; pH stays at 7.5 all season.
Click to expand...

That's nice. My TA is 50-60 and still requires the acid.
 
With the SWG you will have to run your pump a minimum of 12 hrs so the SWG can do it's job, with a 10GPD Stenner and 8.25% run time would be around 3.4 hrs. Since your pool is going to be so large 12 hr run time is not out of the question. Another reason to go with SWG is you will need a fairly large bleach container. At least 15 gal larger if you want to go longer than 10 days and then you have to start thinking about the breakdown of the bleach due to time, and temp.

I was going to go with SWG on our build but have change my mind and we are going with Stenner 10GPD for bleach and 3GPD for acid, our pool is going to be around 18,000 gal and temps are a bit milder where we live. The plan is to use 10% bleach and 34% acid diluted 3 to 1 out of 6 gallon buckets only buying/filling enough for 10 to 15 days. Main reason for the change is the up front cost. I am DIY-ing the install so the 2 Stenners installs are going to run around $500, SWG would have been more like $1800 for Pool Pilot and pHTek. I may still add SWG and a PH probe later but for now it will be the Stenner.
 
I believe the OP stated that he does not have a source of bleach larger than standard retail gallons. If so, you are looking at potentially buying and using 30 gal/month of bleach. That's 30 bottles of bleach that weigh nearly 10lbs each, or almost 300 lbs of hauling liquid from your driveway to the storage tank. Where I live, I have a local shop that sells liquid chlorine in refillable gallon containers and even 2.5 gal carboys. If that were not readily available, Stenners would be totally out of the question based purely on the hauling and disposal aspects.

If you don't have a source of high volume bleach, then you need to seriously factor in how much bleach you can haul and where you will get it from. I've seen people report on here that they have wiped out their local Walmarts buying up every last bottle of bleach on the shelves.

By contrast, once the salt is in the pool, the chloride is in the water and it simply stays there. The SWG converts the chloride to chlorine, the hypochlorous acid destroys the organics and pathogens in the water and is converted back to chloride. The cycle continues with no needed input of an external chlorine source.

Just something to consider....


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The more you guys tell me, the more it looks like a SWG is the way to go with my size pool. You're right... I cannot find bulk chlorine around here and I don't want to lug all that bleach, even to put it into a Stenner tank, for the life of the pool. Now my problem is figuring out how to run a SWG since I had been spending all my time reading up on Stenner systems. We were not planning on going with automation since this will be a simple pool setup, but I've read that with a Pentair SWG, you can't fine tune the percentages without the automation. We are aiming to go with all Pentair products, so tips on what automation would be best for me would be much appreciated.

We are now pretty serious about trying to do this pool as an owner-builder so I feel like I like need to know at least little of what I'm doing before having the plumber and electrician out! We have not decided on the pump we will use yet (I have a thread here that hasn't produced any responses: Help me pick the right sized pump please!!) but perhaps now that we are wanting to do the SWG, that helps narrow down the choices? I know I want at least a 2 speed pump for the cost savings, but maybe a VS might make more sense working with the SWG. I also don't know what size I need based on the volume of my pool. Any advice on pumps would be great too! Thank you so much for the help you've all given so far.
 
For automation, look through the Pentair website or call them (they are actually quite helpful) about the EasyTouch automation system. The EasyTouch load centers can be customized with any number of relays to suit your automation needs as well as have the SWG power supply built in. This way you get one single automation panel to hang wherever your equipment pad will be.

I have the 3HP IntelliFlo VS pump and I can say it is awesome. It has all the power I will ever need to run my pool and I like being able to dial the pump speed way back in the winter time when I don't need a lot of flow. My pool runs all year round so that flexibility is huge for me. The difference in price between that and a comparable 2-speed is, in my opinion, insignificant when you consider the total cost of your build.


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I would go with the VS pump gives you more flexibility. If you live in an area where the pump might get fried by lightning then a 2 speed can be more cost effective since they are less expensive to replace and not that much less efficient for the price. If lightning is not a concern the VS should pay for it's self over time. As for size I have not done any research on that, I would ask the plumbers what they think and take a survey of owners of similar size pools be sure to ask about suggested filter size too.
 
atttech-2 said:
I would go with the VS pump gives you more flexibility. If you live in an area where the pump might get fried by lightning then a 2 speed can be more cost effective since they are less expensive to replace and not that much less efficient for the price. If lightning is not a concern the VS should pay for it's self over time. As for size I have not done any research on that, I would ask the plumbers what they think and take a survey of owners of similar size pools be sure to ask about suggested filter size too.
Click to expand...

For ~ $100 at any hardware store, you can buy a whole-home surge protector that snaps right into your electrical service panel and will completely protect your pool equipment. I have one in my EasyTouch load center to protect my pool equipment.


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