CYA Level Question

Jvance45

Member
Aug 16, 2020
17
Tallahassee, FL
We recently completed construction on our swimming pool and I am working to dial in my chemistry. What is the ideal level to bring my CYA to? When I look at the chlorine/cya chart, it says that 60 is not recommended* for SWG, so I think maybe 70. When I look at the SLAM Chart, it says 70 is not recommended so I'm back to thinking 60. Am I reading this incorrectly? Thank you in advance!

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For a SWG it is recommended to be at 80 as it keeps a more stable chlorine level and the SWG keeps adding chlorine the whole time it is working...

For a SLAM it is not recommended for CYA to be that high as you have to have a higher FC level..

Here is where it gets interesting, as long as your SWG is working and you keep your FC at the recommended level it is really hard to get algae to grow... therefore unless something goes haywire you will be safe from an algae bloom...

I keep my FC at or above 7 at all times, I never let it get anywhere near the minimum.. That target is what you want and at CYA of 80 it says 6.. The 2 times in 8 years I have had to do a SLAM was because my breaker tripped and I missed it for 2 days... My SLAM both those times took about 36 hours and my SLAM was over... but I had to take my FC level to 32 and it takes a lot of chlorine to get there, I hit it fast and keep it at 32, checking every 2 hours until my water sparkles again and I pass the OCLT...

Did I clear it up or make it worse :)
 
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Thank you so much for your insight, this makes a lot of sense but leads me to a new question.

This week, I went to Leslie's to double-check my CYA because I don't trust my eye on the dot test. They indicated that I have a Combined Chlorine over 1 and recommended "Fresh and Clear". I know that TFP recommends a liquid chlorine shock instead but I was surprised to hear that I had an elevated combined chlorine. New pool, cold temperatures, and we have barely been in it.

You mention 2 SLAMs in 8 years and my chlorine has always been at recommended levels. Do you think I should SLAM?

Thank you!
 
Don’t trust anything you get from Leslie’s in terms of advice or test results. I get you’re not confident about your eye on the CYA read but on average your eye with your own quality test is WAY more accurate than a Leslie’s test.

They told me my CyA was going up a lot over a period of 3 tests I had them do for same reason you’re having them do some for you (validate my in home tests). The thing is, I don’t use pucks & weren’t adding any CYA to my water so there’s no way my CYA was going up. They couldn’t give me any sane reason why they were telling me my CYA #s were up each test. At this point I became a hardcore believer in what’s said here about pool stores & Leslie’s in particular.

Now, you can buy control samples from same place you get the TF-100 kit from. Those samples are calibrated to certain #s so as you can test your testing prowess against known / already set #s. It’s dirt cheap to buy these & it will show you that you’re testing is good (if it is).
 
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That's a great point. Well, I went out and tested and I am reading a 0 or maybe a 0.1! The other numbers at Leslie's were pretty close to my home test, so I believed them. Actually, I had 3 tests completed at Leslie's as I attempt to dial this CYA in and each showed combined chlorine between 1 and 1.2. Interesting....

Phosphates in the 3,000's but I'll deal with that at the end of swim season if at all.
 
Don’t trust anything you get from Leslie’s in terms of advice or test results. I get you’re not confident about your eye on the CYA read but on average your eye with your own quality test is WAY more accurate than a Leslie’s test.

They told me my CyA was going up a lot over a period of 3 tests I had them do for same reason you’re having them do some for you (validate my in home tests). The thing is, I don’t use pucks & weren’t adding any CYA to my water so there’s no way my CYA was going up. They couldn’t give me any sane reason why they were telling me my CYA #s were up each test. At this point I became a hardcore believer in what’s said here about pool stores & Leslie’s in particular.

Now, you can buy control samples from same place you get the TF-100 kit from. Those samples are calibrated to certain #s so as you can test your testing prowess against known / already set #s. It’s dirt cheap to buy these & it will show you that you’re testing is good (if it is).
Wow, great advice! I had no idea you could purchase a control. That CYA dot test (until it barely disappears) had me convinced it could be 40 or 60. A newbie getting used to the equipment. Thanks again!
 
What test results do you get with your own kit?
That's a great point. Well, I went out and tested and I am reading a 0 or maybe a 0.1! The other numbers at Leslie's were pretty close to my home test, so I believed them. Actually, I had 3 tests completed at Leslie's as I attempt to dial this CYA in and each showed combined chlorine between 1 and 1.2. Interesting....

Phosphates in the 3,000's but I'll deal with that at the end of swim season if at all.
 
Phosphates are a Leslie’s thing to get you to buy ‘fixes’ from them. The TFP way doesn’t subscribe to phosphates being a problem in a properly maintained pool.

Can’t say it enough..... Leslie’s testing is a Crud shoot at best. In my example above their #s started out being similar to mine but then progressed to total B.S. level. IMO they were trying to work me into thinking I had a developing problem & then we’re going to sell me fixes for those phantom problems 😡.
 
Phosphates are a Leslie’s thing to get you to buy ‘fixes’ from them. The TFP way doesn’t subscribe to phosphates being a problem in a properly maintained pool.

Can’t say it enough..... Leslie’s testing is a Crud shoot at best. In my example above their #s started out being similar to mine but then progressed to total B.S. level. IMO they were trying to work me into thinking I had a developing problem & then we’re going to sell me fixes for those phantom problems 😡.
I'm glad I asked these questions tonight. Great point, and I felt the same way while in the store. The man behind the counter was quick to throw products up on the counter and whip out the highlighter with directions. I never had a pool problem until I walked into the store. Lesson learned. Thanks again!
 
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I just opened the pool and (thanks to this site) will be trying some new ideas for the chemical balances myself this summer. I did my first CYA test yesterday and if I can trust my eyes the level seems to be between 80-90. I have not added stabilizer to the pool for may years (mostly because I did not understand the value of CYA) so I'm curious if a reading that high is accurate.
 
Welcome to TFP @danbacanskas Have you been putting 3 inch pucks in your pool? Each one of those have CYA in them, also any Dichlor and Trichlor has CYA in it..
For the last 10 years I have been using the Omni Synergy chemicals (plus whatever my pool store water analysis said I needed). I have not used the Synergy Initiator in at least 5 years. I was really expecting to see a near zero level of CYA and was quite surprised to see the test water that cloudy.
 
Both. The water was also about 61 degrees when I did the test so that may have added a bit to the high reading. I really appreciate you pointing out that both chemicals I have been using contain CYA. I realize CYA is tough to remove so I'm going to assume I won't need to worry about adding more this summer but I will re-test in July to see if the level of CYA has changed. Thank you.
 
No problem at all, that is one of the things we do here.. It is always better to know exactly what you are putting in you pool and why... That is why you really want to use liquid chlorine as it adds no CYA, just chlorine and salt :)
 
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