Supplemental Sanitizer or Chlorine generator?

[CCWTopeka]

I'm a pool professional who's been dealing with a pool with high demand for years. The pool is just over 40K gallons. There's a spa attached to the same system as the pool that's just under 1K gallons. Sanitation is provided by an IC60. During the heavy parts of the swimming season, I have to run the generator at 100% while its in pool mode and 20% when it's in spa made. I have the spa set to run for 5 hours from 7p to midnight, and then it runs on the pool the rest of the time. I have a very hard time keeping the chlorine levels at the 7.5% of the CYA level on this pool. I have to manually add Sodium Hypo every week to both bodies of water or the chlorine levels just keep falling. The pool gets used A LOT. They basically open their pool up to their church and people from the church use it often, so the bather load is very high. I know I don't have some sort of biological issue, because this is only an issue when school is out. Once the use of the pool goes down, I have no trouble keeping the FC up where it should be and can turn the generator down to more reasonable levels. Because of the way the pool builder designed the equipment pad, adding any sort of additional chlorine feeder is difficult. Currently, there's no room in the plumbing for an additional SWG, and because the equipment is below water level and the single pump nature of the design of the system, I'm not confident in accurately controlling the FC with a liquidator.

BUT, due to issues that don't need explained at length here, I'm going to be replumbing the equipment pad to fix some hydraulic issues the builder created in the way he built the system and installing a variable speed pump and eliminating a second pump the builder was using to run half the spa. Also, because the builder didn't put any kind of equalizer line in-between the pool and spa, the chemistry is often different in both bodies of water and I basically have to treat them separately.

So, here's my question; What can I do to either increase the chlorine generation in the pool, or reduce the chlorine demand? My local Pentair rep is pushing Bioshield, but I'm well aware of how UV is looked upon in outdoor residential pools on this forum. I will say that this pool has an automatic cover and it's kept closed a lot, so maybe the UV would help reduce the demand enough that the SWG could keep up? Since I'm replumbing the entire equipment pad, I'll have the freedom to do as I please for additional sanitation now. My initial thought was to add an additional SWG and have one run at a fixed level and the other controlled by the automation. I'm concerned that if I turn it down enough to work with the spa, it won't do enough for the pool. I'm pretty confident that I can't have both of them controlled by the automation system without upgrading the control board in the automation (It's an old Easytouch8), but I think that's going to be a hard sell due to the expense, plus Pentair is phasing out the EasyTouch8 and wants us to upgrade the boards to the new IntelliCenter systems. As I've said before, I'm concerned about the liquidator working due to the equipment being nearly 6' below the water level in the spa, and 3' below the pool water level. I'm also concerned about control since there's no equalizer line, trying to get it set to a level that works for both bodies of water seems impractical.

I'd love to hear any ideas anyone might have for how to deal with this.

 

[CCWTopeka]

As I hit post on that, I just had the idea that maybe I could use 2 liquidators? The suction from both would have to Tee together to feed into the pump, but the inlet could feed into them separately, allowing me to set to different levels based on which body of water the pump is pulling from. A potential issue I could see with that would be the spa tank getting too low while running on the pool side. Conceptually, the outlet float should close and prevent that, but I'd hate to rely on that all day, every day.

Has anyone done anything like that?

 

[jmastron]

First -- what is the CYA level you're maintaining, and what is the allowed range in your area? If allowed, keeping CYA in the 60+ppm range with a SWCG (and keeping the FC at proportionally higher levels) will reduce the FC loss to the sun at least by a lot.

Second, I'd be tempted to put in a second IC60 (I believe often plumbed in parallel), vs adding a different mechanism to the mix.

Adding chlorine manually once a week (or even more often) during the peak season also doesn't sound like that horrible of a solution, as long as the SWCG is then able to keep it well above the minimum throughout the rest of the day.

 

[wireform]

CCW,
Hi and welcome. To begin you haven't mentioned anything about your testing methods and we here are helping via your own test results from one of our recommended test kits. Link for all will be below. Also pictures of the pool and spa along with pictures of the equipment pad from various angles can aid in answering some of your questions. I have no idea if your spa is a separate entity from the pool and just uses the same equipment or is the spa part of the pool. If the spa is an integral part of the pool you may be able to use the SWCG for the pool and have the spa continually overflow and mix with the pool again as I am unsure of the plumbing I can't advise yet. Check out the links below.
Pool Care Basics
Test Kits Compared
FC/CYA Levels
SLAM Process
Overnight Chlorine Loss Test
PoolMath

 

[CCWTopeka]

I've been taking care of this pool for close to 10 years now. I've run various CYA levels. Because we close pools for the winter here, I don't like to have the CYA too high when I close due to the high chlorine demand that it often creates in the spring the following year. Last week the CYA was at 58ppm. I have tried CYA levels up to 80ppm on this pool with limited success. At around 80ppm, I was able to get the IC60 turned down to around 95% on the spa and 18% on the pool. The following year, the demand was extremely high and I ended up having to drain most of the pool and refill it to deal with the demand. Due to the 40K gallon size of the pool, the water and salt expense was high, so I don't want to run it that high again.

I'm leaning towards an additional IC60 plumbed in parallel, but there's no easy way to get the EasyTouch to control both cells, so the 2nd cell would have to just be run at a fixed percentage. I'm doubtful that will work with the pool/spa combo with no equalizer line system I'm dealing with. Maybe I could run the 2nd cell on just the pool line and increase the spa run-time to get the EasyTouch's 20% limit to work ( I could strangle whoever thought that was a good idea). Now that I'm thinking that out loud, that may be the easiest route.

I'm already shocking the pool weekly, but it's still barely enough.

 

[CCWTopeka]

CCW,
Hi and welcome. To begin you haven't mentioned anything about your testing methods and we here are helping via your own test results from one of our recommended test kits. Link for all will be below. Also pictures of the pool and spa along with pictures of the equipment pad from various angles can aid in answering some of your questions. I have no idea if your spa is a separate entity from the pool and just uses the same equipment or is the spa part of the pool. If the spa is an integral part of the pool you may be able to use the SWCG for the pool and have the spa continually overflow and mix with the pool again as I am unsure of the plumbing I can't advise yet. Check out the links below.
Pool Care Basics
Test Kits Compared
FC/CYA Levels
SLAM Process
Overnight Chlorine Loss Test
PoolMath

I'm using a LaMotte Pool Manager PM-51 test kit.
This isn't a pool I own. I'm a pool professional taking care of this pool for a customer. I'm apprehensive to post pictures of their property online.
I apologize if my original post was unclear. The pool and spa are separate bodies of water, with a shared equipment system, but the spa lacks an equalizer line with the pool. If the builder had put an equalizer line in like he should have, this situation would be MUCH easier to deal with. I'd simply add a second SWG in parallel. Unfortunately, that's not something that can be fixed without major concrete work. So having the spa continually overflow to mix with the pool isn't possible.

 

[Newdude]

An IC60 in 40k gallons will produce 6 FC per 24 hours. That should be plenty. Something is likely consuming the chlorine as fast as it's produced.

You need to prove there is no overnight loss with an Overnight Chlorine Loss Test. If you lose FC overnight with no UV or bather load, it's an organic problem, not a mechanical one.

If you pass the OCLT then you run an overnight gain test.

If FC has no problem building overnight, then we look at the CYA.

If the FC doesn't build overnight, then we look at the why the cell isn't doing as it should, such as not generating on one of the polarities and only generating half the time it should.

 

[CCWTopeka]

An IC60 in 40k gallons will produce 6 FC per 24 hours. That should be plenty. Something is likely consuming the chlorine as fast as it's produced.

You need to prove there is no overnight loss with an Overnight Chlorine Loss Test. If you lose FC overnight with no UV or bather load, it's an organic problem, not a mechanical one.

If you pass the OCLT then you run an overnight gain test.

If FC has no problem building overnight, then we look at the CYA.

If the FC doesn't build overnight, then we look at the why the cell isn't doing as it should, such as not generating on one of the polarities and only generating half the time it should.

I'll work on getting those results, but the pool is on the other side of town and I'm swamped, so it will be a while before I have time to do all of that.

And so we're clear, it's not that it doesn't hold a FC reading at all, it does. But I struggle to keep it up to the 7.5% of CYA value without having to manually add chlorine when I come once a week. This is only an issue from late May to early September. Outside of those months, the pool doesn't get used as much due to the kids being in school, and I'm then able to turn the generator down to much lower levels.

 

[Newdude]

I'll work on getting those results, but the pool is on the other side of town and I'm swamped, so it will be a while before I have time to do all of that.

Oh yeah. You don't live there. It will have some challenges.

And so we're clear, it's not that it doesn't hold a FC reading at all, it does

It struggles to hold the 6 FC the IC60 creates, which is above the 3 or 4 ppm daily loss that's expected in KS this time of year. So then we have 3 choices, listed in order of how often we see them.

1) organics consuming the FC
2) cya needs increasing
3) cell issues.

Do what you can, when you can, and report back.

 

[DrewLG]

As I hit post on that, I just had the idea that maybe I could use 2 liquidators? The suction from both would have to Tee together to feed into the pump, but the inlet could feed into them separately, allowing me to set to different levels based on which body of water the pump is pulling from. A potential issue I could see with that would be the spa tank getting too low while running on the pool side. Conceptually, the outlet float should close and prevent that, but I'd hate to rely on that all day, every day.

Has anyone done anything like that?

For my Liquid Feeder (newer version of the Liquidator), I deliberately plumbed the tank inlet to the Pool Return line AFTER the Return valve, so the tank only fills (and allows the tank output valve to open) while the system is in Pool mode, not while it's in Spa mode. Works great, and does what you're trying to do: Prevents the Liquid Feeder from overchlorinating the spa.

Of course, the Liquid Feeder has its own set of potential issues:

• You'll need to experiment with its output valve to determine the right flow level.
• You may periodically need to clean accumulated scale out of the hoses. @Chuck_Davis describes a mod that makes the process easier here: HASA Liquid Feeder (Liquidator Replacement) - Recommended Modifications).
• You'll need to add liquid chlorine to the Feeder on a regular basis. 8 gallons of 12.5% provides 24 ppm of FC to a 40K-gallon pool, so if you're relying on the Liquid Feeder to add 1.5-2 ppm per day, you'll have to add 4 gallons of liquid chlorine every week.
• The Liquid Feeder is physically large and takes up a fair amount of space on the pad.
• Etc.

For those reasons and others, I'm not at all sure that adding automated chlorine feeding/generation is the answer here.

Is it feasible to raise the FC of both bodies significantly above 7.5% CYA? Pool water is safe for people and equipment with FC levels up to 40% CYA, so if you're visiting the pool once a week, couldn't you just use liquid chlorine to raise the FC level to, say, 25% of CYA? Than, even if the SWCG can't keep up with demand during that week, you'll have provided a lot of room for FC to fall before it drops below 7.5%.

 

[CCWTopeka]

Apparently all I needed to do was post about the problem on here and it would finally present itself. No exaggeration, I've been fighting this issue for around 8 years. The problem? The Easy Touch is randomly shutting the pump and generator off even though it's not programmed to do that. I've had this happen one other time about 15 years ago. I had completely forgotten about that until today when I went to check the chemistry and everything was off. I immediately questioned the customer about it and they said, "Oh, yeah it turns off like that sometimes. We just thought it was supposed to do that. It always comes back on, so we never thought anything about it." I told the customer to tell me the next time it turns off and told them how to turn it back on. I went ahead and deleted all schedules and reset them (there's only 2, 19 hours for the pool, 5 hours for the spa). I don't expect it to fix it though. This would completely explain all the issues I've had.

 

[Newdude]

Apparently all I needed to do was post about the problem on here and it would finally present itself

We like to help in any way possible. We will gladly take that win. Cheers.

 

[DrewLG]

The Easy Touch is randomly shutting the pump and generator off even though it's not programmed to do that.

Do the people using the pool have access to pool controls? If they're doing something like manually switching from pool to spa mode, then switching the spa off when they're done -- or allowing an egg timer to shut it off -- it's possible for the EasyTouch to leave everything off until the next scheduled start time.

 

[CCWTopeka]

Do the people using the pool have access to pool controls? If they're doing something like manually switching from pool to spa mode, then switching the spa off when they're done -- or allowing an egg timer to shut it off -- it's possible for the EasyTouch to leave everything off until the next scheduled start time

Yes, there's access to the control panel, but in this particular incident, I'm confident that nobody had touched anything because they had JUST gotten back from being out of town for a week (they were still unloading their vehicle) and the pool house were the control panel is was still locked from them being gone. They just texted me this morning and said it was off when they got up this morning and that they turned it back on. Nobody has touched the pool since Wednesday because it's been cloudy and cool here the last few days, so nobody has wanted to swim.

After reading your post, I asked them specifically about things getting turned off and they were confident that wasn't happening. They said that when people come, it's planned ahead of time so they are the ones to get things ready. The church people don't touch the controls. They also said the spa almost never gets turned on because it usually gets used more like a wading pool for little kids. The husband assured me that he was 100% sure that in the times that they do turn the spa on to heat it up, that he always make sure that the pool is running again when everyone leaves.