Why does my CYA go down?

[Maestro]

I know I've read here that once CYA is in the water it stays there, and the only way to lower it is to drain and refill. But my level has fallen consistently this season, and I think that's why I had to do my first SLAM last week.

Here are the numbers:

5/15: 70
5/24: 60
5/31: 50
6/10: 45
6/18: 50
6/25: 30
I then added a little over a pound of stabilizer which was all I had on hand.
6/29: 50
7/4: 50
That's the day I started the SLAM; FC was 0
7/8: 50
7/10 (today): 35

I don't think I topped off the pool with fresh water more than once before the SLAM, I only backwashed once or twice, and I don't have any kids splashing water out of the pool. I did backwash a few times during the SLAM which lowered the water level, and I topped off yesterday.

Any ideas on what's going on? I plan to add more stabilizer today to get it back to 70 since my SLAM is over.

 

[zea3]

How are you testing the CYA? How often do you backwash or vacuum to waste? Does your pool have an auto filler?

 

[Paul & Crystal]

I find that my cya holds better if I buy a higher quality such as Protech from the pool store. I used Clorox once and it did nothing.

 

[Maestro]

How are you testing the CYA? How often do you backwash or vacuum to waste? Does your pool have an auto filler?

I use a TF-100 test kit and do it by the book -- fill the sample bottle with pool water up to the label and R-0013 solution the rest of the way, shake, wait 30 seconds, shake again, and then pour it into the testing tube until I can't see the black dot.

Except for the SLAM, I don't backwash more than once a month, and I don't have an auto-filler.

- - - Updated - - -

I find that my cya holds better if I buy a higher quality such as Protech from the pool store. I used Clorox once and it did nothing.

Darn it, I just put three pounds of Clorox stabilizer today since I opened this thread! The label says "Cyanuric Acid...100.0%." What could go wrong?

Does anyone else out there have different results from different brands of stabilizer?

 

[zea3]

We have had some complaints about the Chlorox brand stabilizer this year. I don't know if it is mis-labled or what the problem is. Normally when we see drops in CYA the top reasons are testing error, unknown leak in an auto filler that continually adds and drains overflow water from the pool, and a bacterial conversion that seems to occur mainly in swampy pools (but is still pretty rare).

 

[Newpoolcrazy]

Don't mean to hijack this thread, but wanted to add that we too tried Clorox brand and my CYA didn't change one bit either. In fact, that's one of the questions I was going to ask about CYA (best brands). Will start another thread for my other Q's, but we need to put the word out not to bother with the Clorox brand of conditioner/stabilizer as it just plain doesn't work.

I find that my cya holds better if I buy a higher quality such as Protech from the pool store. I used Clorox once and it did nothing.

 

[pookiesunshine]

funny. i just checked at the clorox pool products web site and found one review of it from someone in Orange, MA. 1 star, said it didn't work. funny strange, not funny haha. wasted effort is never funny.

 

[Maestro]

I'll retest my CYA in a couple of days. Then I'll post again to this thread to let you know if the Clorox stabilizer I just added worked.

Then I'll keep an eye on it till the end of the season and keep good records about backwashing and topping off the water level. If anything looks wrong I'll keep this thread going. Anything to avoid having to do another SLAM!

 

[Maestro]

Well, here's the update, and it's not great. My CYA had dropped to 35 just before I added the three pounds of Clorox stabilizer last week. I tested two days later and found the level had risen to 60, so I went ahead and added the fourth pound to finish the bottle and hopefully get the level up to 70, my target.

We had heavy rains Thursday and Friday so I had to lower the water level a few inches. I figured that would affect the CYA level, but it should have been only slightly. When I checked the CYA today, it's down to 50!

I guess the problem could be bad stabilizer, like you've suggested. No more Clorox for me! I've ordered a different brand – Kem-Tek. I really hope nobody out there has anything bad to say about that one...

I'll put it in the water later this week and let you all know how it works out.

 

[tre]

I found this thread because I'm having the same problem. I was starting to think I had a leak in my pool because I can't understand how my CYA went from 60 down to 40 in 10 days. The leak theory is out because I turned off my auto-fill and it has not rained but my CYA still went down.

Full story - My CYA was at 40 in my SWG pool after loads of rain and draining some water out. I went to Wal-Mart and purchased Clorox CYA. I added Clorox CYA to bring the level up to the 60-70 range. I tested a day or two after I added 1/2 the bottle (or so) of the Clorox CYA and I was at 60. I tested again to be sure and still got 60. Now, 10 days later, I'm back down to 40 again. I guess this Clorox CYA is junk. Going to shell out big money at the pool store I guess.

 

[EastCoast]

I use the Clorox brand of conditioner and have seen no problems.