New Pool Owner Worried about High CYA

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W

WaarrEagle

Member
Jun 20, 2022
20
Houston, TX
Pool Size
19000
Surface
Plaster
Chlorine
Liquid Chlorine
First time pool owner but I am a super DIY'er with everything else. I decided to let the pool company keep servicing until I could get a handle on the new house. So far this season we have had multiple outbreaks of water "issues" - algae, cloudiness, etc. I have been reading here, getting educated, and watching my CYA trend higher per pool company monthly tests:

DateCYA (ppm)
11/11/2021​
50​
12/16/2021​
40​
1/13/2022​
40​
2/17/2022​
40​
3/17/2022​
50​
4/15/2022​
75​
6/16/2022​
100​

I purchased a K-2006 kit and performed my own tests today:
FC - 4.0
CC - 0 (i think?)
PH - 7.4
TA - 80
CYA - 120 (100+ with basic test, repeated with diluted method)
CH - 400

I fear CYA is going to get beyond repair soon. I am in Houston and water temp is 90+ so I am wondering if I could stop the pool company tablets and manage liquid chlorine to let the CYA trend down. Can I just turn my chlorinator down to 0?

This photo is from earlier this week. It is like a dust on the bottom of the pool and easily gets stirred up. What is it and would raising FC resolve it? Or do I need a SLAM?

In-ground plaster pool, tablet chlorinator currently set to max output, fixed speed pump, cartridge filter
 

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Hi! I'm sure others will provide some specific guidance but, in the meantime, I'll jump in with my thoughts as a new pool owner. Your CYA is only going to decrease if you remove some water via draining or with splash out (minimal). At the level of CYA you are at, you'll need a very high amount of chlorine to keep the pool sanitized (search CYA/chlorine chart on this site for the corresponding amount of one to the other). I'd stop the tablets ASAP as they likely have CYA in them. Use liquid chlorine (if SWG is not an option) but I think you have to get the CYA down to have it be a manageable amount. I'll leave the drain conversation to the experts :) Good luck!
 
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A 50% drain and refill should land you on a manageable CYA number.

I did that several years ago and set up a siphon running at the same rate as a garden hose. It takes more water that way, but you can keep the pool open and running the whole time and don't have to screw around with sump pumps. I did the math to estimate how long it would take and was pretty close in the end.
 
You have three options, really.

1) exchange out water, about 50-75%, to bring CYA down to manageable levels. I don’t know how feasible that is in Texas.

2) reverse osmosis. My understanding is this is expensive and will still cause you to lose some water but it may be cheaper than the exchange if water is really expensive.

3) maintain a REALLY a high FC level. This will be difficult at 120ppm CYA. Your FC would need to be never below 10ppm, and at 10ppm and higher, the pH test doesn’t work well. You’d have to stay on the FC levels like a hawk, letting it just barely get down below 10ppm, adjust pH, immediately add FC back in. If you ever had to SLAM you would be looking at maintaining FC at 48ppm (!!).

I would do the following in your situation:

- Tell pool company that no chlorine goes in the pool except liquid. You will also be supplementing daily to keep FC levels where they need to be. (They may object and if they refuse, time to say goodbye to them.) Get any pucks in any chlorinator or in the pool out immediately.

- Make sure pH is about 7.2, adding some muriatic acid if needed to bring it down.

- Raise FC up to above 10. Probably more like 14-18, which would be the target with 120ppm of CYA. Liquid chlorine ONLY.

- Perform an Overnight Chlorine Loss Test to see if a SLAM is in my immediate future.

If the OCLT passes, then I’d consider the hassle of maintaining such a high chlorine level, including letting it drop to the Danger Zone to test pH weekly or so, then adjusting pH and pushing FC back up, against the cost of replacing water or reverse osmosis. If the OCLT fails, you pretty much are locked in to reducing CYA right away to have a reasonable SLAM.

If you don’t reduce CYA now, and are able to keep a high FC level with no algae, then keep an eye on the CYA level. Heat will break it down slowly over time. If expecting a storm, drain an inch or two off the pool and let the rain refill. It won’t do much with one rainfall but over time can help to bring CYA back down.
 
Thanks all for the input. Sounds like I have some homework with an OCLT and I also need to work logistics of getting liquid chlorine (i currently have none) and talk to the pool company. I am leaning towards a partial water replacement but my drain situation is not great and I need to check the costs. We are nearing drought conditions so I may lose my chance if I dont act soon.
 
If you MUST use a weekly pool maintenance company, the only way they can manage a pool without tablets (and CYA increase) is by installing a salt water chlorine generator. You pool will receive a daily dose of chlorine, so when the pool guy comes, he'll check/adjust pH, clear skimmer baskets, and brush or vacuum. This something you can take over and save yourself the monthly bill.

Let us know if you need help deciding on a course of action.

Best wishes!
 
Home Depot, Walmart, Ace and Lowe's for 10.5% liquid chlorine. Pinch-a-Penny for 12.5%.
Can always use regular ol' bleach, usually around 6%. Be careful choosing your bleach!
No additives allowed such as chloromax, fragrances, splashless or other silliness.
 
Lilypad said:
Home Depot, Walmart, Ace and Lowe's for 10.5% liquid chlorine. Pinch-a-Penny for 12.5%.
Can always use regular ol' bleach, usually around 6%. Be careful choosing your bleach!
No additives allowed such as chloromax, fragrances, splashless or other silliness.
Click to expand...
I haven't seen any non-silly bleach at any grocery store around here in a couple years. It's a minefield now.
 

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A couple updates. Pool service came on Thursday, measured 0 chlorine, and put 4 gal liquid in + 4 tabs + turned the chlorinator to max. I have a call in to their service manager to discuss changing to liquid only.

I stopped by my local PinchAPenny and their liquid chlorine is only 10%. They said something about it being 12.5 when they receive it but 10% in the 2.5 gal jug. The jug labels listed 10.0% as well. Shrinkflation??

Also, I tried an OCLT but must have messed it up. I turned off my chlorinator and let the pool run for 30 minutes before testing last night. FC of 9.6. This morning i turned the pump on for 30 minutes, tested, and got 11.0. I retested with the smaller sample size and got 10.0. Will try again.
 
They said something about it being 12.5 when they receive it but 10% in the 2.5 gal jug.
Click to expand...
There is truth in that statement. LC at 12.5 is "hot" and deteriorates pretty quickly. Many, many chlorine distributors sell to stores at 12.5% but by the time it get's into your hands, it is usually closer to 10%. Nothing dishonest there at all.....just the nature of how quickly 12.5 becomes 10%
 
Hi Plano neighbor. GET RID OF THE PUCKS. Who is the pool company? I recently fired Cool Pool People - they were dumping pucks in my pool like crazy - more than even needed for my size pool and simultaneously telling me to get a automatic chlorinator AND do water exchange. The final straw was when they sent some dude out who didn't even know the size of my pool and he dumped in 4 pucks. Anyway, I'm on month 3 of all liquid chlorine.
 
I am committed to making the switch to DIY liquid chlorine but will likely defer it until September when I should have more time to do a proper drain/refill/SLAM. Until then I soldier on with the pool company. Algae has ticked up slightly a couple times but they seem to get it back under control.

Check this out tho... I was assessing my pool lights for possible replacement when I drain. I thought one of the housings was compromised. Turns out it has a removable cover and the inside was covered with algae. All of them had it to some degree. I'm sure this was not helping my chlorine situation as I know at least 1 light has been this way since I moved in last November. Are these covers needed or can I run without them? I believe they are early model SRSmith LED's. One of the covers was missing anyway and replacements are ~$20/ea.
 

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This is the weekend for my big drain and refill! CYA is measuring 160 now and I have had constant algae for weeks. Pool company was fired moments ago. I have a pump and will start draining tomorrow. Should I immediately start adding liquid chlorine during the refill process, or wait until full?
 
WaarrEagle said:
Should I immediately start adding liquid chlorine during the refill process, or wait until full?
Click to expand...
Wait until you refill and let the new water mix really well for a few hours before grabbing a sample for testing. Then start your adjustments.
 
It has been a busy weekend! Drained ~3/4 and refilled. CYA down to 50, was hoping for a bit lower but should work. After mixing for a bit I got the following:
FC - 1.0
PH - 7.8
TA - 140
CH - 180
CYA - 50

I added muriatic acid for PH and LC to start the SLAM. FC is now holding pretty well at 20. Should I worry about CH during the SLAM?
 

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