CYA and FC trade off in the TEXAS SUMMER HEAT

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Kobiano

Member
Apr 25, 2022
11
Dallas
My CYA is 40, and my pool water is pristine and clear. However, I find it irritating that after shocking my pool to levels of 10 FC, after 1 day of Texas Summer Sun, my FC drops drastically to 3 or so. Does anyone else have this problem in Texas? If so, would you recommend increasing CYA to say 50? Curious to what everyone's CYA level is in Texas..

Thanks in Advance for any input!
 
Can't answer with my own experience as I'm on the north side of the country, but raising to 50ppm would be perfectly fine. Just keep your FC higher to boot, but it will offer more protection from the sun.

You don't need to "shock" your pool, though. If you have problems with cloudiness/algae showing/etc. you should follow the SLAM Process. Doing that before raising CYA is definitely recommended. If you are just raising it to raise it high periodically, know that it's not necessary to do so if your FC doesn't fall below the minimum on the FC/CYA Levels. Raising it that high is just going to lead to wasted chlorine. :)
 
I would first suggest running an overnight loss test, just to make SURE it's the sun before you increase CYA. Increasing CYA when you have active algae is a costly mistake. It will take so much more chlorine to get rid of it.
You should do this with your own test kit, not pool store OR STRIPS. Not sure how you are testing.

I'm in central Arkanasas, similar weather I would assume to you. I had to increase my CYA to 60 in order to keep up with it the last two years... my pool is in direct sun the entire day and the UV index is nearly always "Extreme"..
Don't go there all at once. Increase by 10ppm until it's acceptable...but, you will always be losing 3-4ppm in the daytime in that climate in my experience.
A salt water generator is the way to go in my opinion.
 
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C3Cl3N3O3 said:
I have as much direct sun as you can possibly get at my pool in SC. My CYA is 40 and I usually see 3 ppm FC loss on a sunny day. 7 ppm loss indicates a problem.
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I figured it out.... Got my CYA tested from multiple sources and it was reading 24....turns out that I forgot to factor in 3 rounds (about once a week since my CYA reading of 40) of Texas thunderstorms that dropped many inches of rain. No wonder my FC was dropping quicker than anticipated in the Texas heat.

FC drop test at night was good, no drop in FC. Pool is as clear as it can get and I've already shocked it just to be safe.
 
I'll join in that scold. Our advice centers around your own good testing.

You should not have a 7 ppm daily loss of FC even if your CYA is less than 40. Secondly, rainwater is not relevant to CYA loss unless your pool overflows.

I think you still have an algae problem
 
duraleigh said:
I'll join in that scold. Our advice centers around your own good testing.

You should not have a 7 ppm daily loss of FC even if your CYA is less than 40. Secondly, rainwater is not relevant to CYA loss unless your pool overflows.

I think you still have an algae problem
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Fair points....but my overnight FC loss test passed with flying colors....if I did have an algae problem...wouldn't it had dropped overnight? It passed back to back nights...also, my pool would never flood, I have a drain built in to prevent flooding....
 
Kobiano said:
Fair points....but my overnight FC loss test passed with flying colors....if I did have an algae problem...wouldn't it had dropped overnight? It passed back to back nights...also, my pool would never flood, I have a drain built in to prevent flooding....
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Can’t answer your questions because we don’t know how you’re testing and with what…

Bad testing often leads to bad results.

If your pool overflows, and by that we mean simply replaces pool water with rain water, then yes, your chemistry will change.
 
reggiehammond said:
Can’t answer your questions because we don’t know how you’re testing and with what…

Bad testing often leads to bad results.

If your pool overflows, and by that we mean simply replaces pool water with rain water, then yes, your chemistry will change.
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Testing via Taylor test kit, aquacheck 7 test strips, and finally....I went to get confirmation at the local pool store and at 2 Leslie locations near my house....

And yes...I'm pretty sure my pool chemistry change based on the amount of rainfall we've gotten ... 6-8 inches accumulation each time.

I still point back to my 0 FC overnight loss 2 nights in a row...and yes, I used the little drops from Taylor....
 

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Excellent! Don’t bother with the other testing methods and trust your kit.

If you’re not losing overnight but losing excessively during the day, then go ahead and up your CYA. Just be sure you keep FC in range for the new target. :)
 
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Kobiano said:
Testing via Taylor test kit, aquacheck 7 test strips, and finally....I went to get confirmation at the local pool store and at 2 Leslie locations near my house.
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Would you ever cheat off the dumbest kid in class because he gets it right sometimes ? (Pool store). Of course you wouldn't. You'd take your chances with your 94% average and if you were a little off, you still did great.

Or even worse by cheating off the kid who is taking the class for the 3rd time. (Test strips)
 
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Newdude said:
Would you ever cheat off the dumbest kid in class because he gets it right sometimes ? (Pool store). Of course you wouldn't. You'd take your chances with your 94% average and if you were a little off, you still did great.

Or even worse by cheating off the kid who is taking the class for the 3rd time. (Test strips)
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This made me laugh 🤣.

Thanks for the help everyone!
 
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Also...I found this thread from last summer discussing the very same conerns that I had about high FC burn off due to low CYA....

CYA Level for Summer

I'm getting some pretty substantial FC burnoff as summer heats up here in Texas (like 4.5 parts per day). I show CYA at 40. Does it make sense to bump it up to 50 to help manage this?
www.troublefreepool.com www.troublefreepool.com

It seems like the conclusion there is to set CYA around 50.....and here my CYA was under 25....so it wasn't a reach to say that my FC burn off was higher than the usual.
 
Kobiano said:
My CYA is 40, and my pool water is pristine and clear. However, I find it irritating that after shocking my pool to levels of 10 FC, after 1 day of Texas Summer Sun, my FC drops drastically to 3 or so. Does anyone else have this problem in Texas? If so, would you recommend increasing CYA to say 50? Curious to what everyone's CYA level is in Texas..

Thanks in Advance for any input!
Click to expand...
Im at 50 and lost 2.5 during yesterday's "extreme UV". Once I solve my other problem I will probably bump mine to 60. I dont want to be out here every 24hours adding stuff.

I also did overnight chlorine tests and no problems so Im certain its not algae. One thing you might want to do is make sure if you have a variable speed pump add near a return with a high cycle and try to add liquid chlorine after sun down.
 
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MikeLikesPools said:
Im at 50 and lost 2.5 during yesterday's "extreme UV". Once I solve my other problem I will probably bump mine to 60. I dont want to be out here every 24hours adding stuff.

I also did overnight chlorine tests and no problems so Im certain its not algae. One thing you might want to do is make sure if you have a variable speed pump add near a return with a high cycle and try to add liquid chlorine after sun down.
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Thanks for the feedback Mike....your results give me HOPE!
 
Just to weigh in as a DFW resident:

In May, I was losing about 3ppm daily with my CYA at 40.

As the June drought with 100+ daily temps began, I bumped my CYA up to 50. I now consume about 3-4ppm daily. I do also get direct sunlight the entire day.
 
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