Proper CYA level for salt pool

[Quickstep192]

I recently converted my pool to a salt cell. After getting the pool chemistry balanced and having the salt cell run for a couple of weeks, I decided to try the super-chlorinate feature on the salt cell. The chlorine level stayed very high for a several days, so I thought I had created a chlorine lock situation and put some chlorine shock in the pool to see if that would break the chlorine lock. Now, five days later, my chlorine reading is still off the charts. My local pool store's test computer recommends 80-150 CYA. The Pentair instructions recommend 30-50 CYA. Is it reasonable to assume that's my problem?

If so, what's the best way to reduce the CYA level? Can it be done without draining/refilling? I live near the water and don’t want to send all that chlorinated water in there if I can avoid it.


I sure appreciate any help.

 

[Rancho Cost-a-Lotta]

Welcome to TFP!

I read your intro post and it doesn't look like you're too thrilled about the pool and the maintenance it requires. Realize though, that keeping the pool looking nice will require some work. Your SWG will make things easier, but you do need a proper test kit to ensure it's doing it's job. The link below has a section on test kits. The test kits at Tftestkits.net provide the best value. We don't trust pool store test or advice.

The most critical measurement of your pool is the CYA level. Once you know that, you'll know what level of FC is required according to the FC/CYA Levels.

If your CYA level is high, the only way to reduce it is through water exchange or reverse osmosis. Get the kit, post up some results, and we can provide advice from there.

Pool Care Basics Archives

Your one-stop shop for all things TFP to include: ABCs of Water Chemistry, Recommended Chemicals/Levels, Test Kits, Troubleshooting, and much more!

www.troublefreepool.com

Best wishes!

 

[Quickstep192]

Thanks for the kind welcome. You're right, I'm not to thrilled about the pool, but I recognize there's some work involved to keep it looking good.

My CYA is 93. I've read varying advice about CYA levels for salt. The computer generated report from the local pool store says CYA should be between 80-150, so I was pretty pleased with 93 being toward the middle of the range.

Free chlorine is 13! And, there's no sign of it burning off. It's been that way for about 5 days with the salt cell off and full sun most days.

My other numbers look pretty good (I think

Ph is a little high at 8.1, but the person at the pool store says that's because the chlorine is so high

Hardness is 258
Alkalinity is 116
Salt is 3500

I sure welcome any guidance.

 

[proavia]

Welcome to TFP!

"Chlorine lock" is a myth.

Chlorine lock...is it real and what's the remedy?

I have an 8 yr old, 25,000 gallon, chlorine pool. This summer for the first time we could not get the free chlorine level to register after adding large amounts of shock and turning the chlorinater on high. All other test readings stayed within the normal ranges and the water was clear. After...

www.troublefreepool.com

Using Super Chlorinate on your SWG brought your FC up. Adding shock increased the FC even more.

Suggest you read thru Pool Care Basics
TFP methods require accurate testing of your pool water. You won't get that at the pool store. We recommend self testing using one of the recommended test kits - Test Kits Compared.

The one test the PS gets wrong more often than not is the CYA test.
Testing your own pool water will provide a better understanding of what your pool needs.
Time required for testing is less than 5 minutes per day and maybe 20 minutes once or twice a month.

 

[Bperry]

Thanks for the kind welcome. You're right, I'm not to thrilled about the pool, but I recognize there's some work involved to keep it looking good.

My CYA is 93. I've read varying advice about CYA levels for salt. The computer generated report from the local pool store says CYA should be between 80-150, so I was pretty pleased with 93 being toward the middle of the range.

Free chlorine is 13! And, there's no sign of it burning off. It's been that way for about 5 days with the salt cell off and full sun most days.

My other numbers look pretty good (I think

Ph is a little high at 8.1, but the person at the pool store says that's because the chlorine is so high

Hardness is 258
Alkalinity is 116
Salt is 3500

I sure welcome any guidance.

Your local pool store results won’t be accurate. It’s hard to believe but true. The CYA test is the worst for them.

That said, if your CYA level is really 90, then a FC of 13 is no problem. Have you checked the FC/CYA chart referenced above? It gives you the proper levels. The pool store is using old recommendations that didn’t take CYA into account.

Your FC will burn off on its own over time, don’t worry about it, or lower your SWG %

 

[Mdragger88]

Tfp recommends swg pools to have cya between 60-80ppm & to chlorinate according to the FC/CYA Levels
A fc of 13 with a cya in the 90’s (if that is accurate) is fine. It is safe to swim with fc anywhere between minimum & slam level for your cya. Which would be between 4ppm & 35ppm.
Trying to follow their recommendations & tfp’s will only confuse things.

 

[Quickstep192]

I have a test kit that can test for CYA. It's the kind where you mix 7ml of R13 into 7ml of water then fill a test tube until the dot in the bottom of the test tube just disappears. The test is a little dicey since what constitutes "just disappears" is a little subject to interpretation, but it reads 90.

I'm not concerned about getting in the pool, I just want to make sure I don't get algae.

Also, the recommendation in Pentair owners manual says CYA should be 30-50.

 

[Bperry]

I have a test kit that can test for CYA. It's the kind where you mix 7ml of R13 into 7ml of water then fill a test tube until the dot in the bottom of the test tube just disappears. The test is a little dicey since what constitutes "just disappears" is a little subject to interpretation, but it reads 90.

I'm not concerned about getting in the pool, I just want to make sure I don't get algae.

Also, the recommendation in Pentair owners manual says CYA should be 30-50.

Cya of 30-50 is fine. TFP users have found they can get away with a higher CYA value to protect the chlorine a little more.

 

[Mdragger88]

I have a test kit that can test for CYA. It's the kind where you mix 7ml of R13 into 7ml of water then fill a test tube until the dot in the bottom of the test tube just disappears. The test is a little dicey since what constitutes "just disappears" is a little subject to interpretation, but it reads 90.

I'm not concerned about getting in the pool, I just want to make sure I don't get algae.

Also, the recommendation in Pentair owners manual says CYA should be 30-50.

U may want to do the diluted version of the test to confirm the 90 - also do the test outdoors in bright light , back to the sun for the most accurate results. If it reads “between” the lines round up & chlorinate accordingly.
Step 8

CYA - Cyanuric Acid Test

Cyanuric Acid (CYA) is the chemical name for what is commonly referred to as Stabilizer … Read more…

www.troublefreepool.com

If u follow the FC/CYA Levels and never fall below minimum for your cya then algae or other nasties shouldn’t be an issue.

 

[Quickstep192]

If you’ve seen my other thread, I’ve been challenged with a chlorine level that won’t drop.

The original test kit I was using shows chlorine level off the chart. As few as 2 drops of OTO would turn the sample water orange (not yellow, orange!).

Today, I tested with a different kit and that other kit shows the chlorine level as 2. The second set is the type that uses two reagents to perform the test.

I know no one trusts test strips, but I tried test strips and they validate the results of the second test.

It seems likely that the OTO reagent is bad. Is that likely?

 

[mknauss]

It is possible.
Can you fill out a signature and show what test kit brand/model you are using, along with pool details? Really helps us help you.

Create Your Signature - Further Reading

www.troublefreepool.com

 

[Donldson]

The best way to find out is to test the chlorine with an FAS-DPD test and get the actual level. That will solve the problem, everything else would just be throwing out guesses.