Where did my cya go????????????

[mepot101]

My pool turned cloudy last week, when I tested it my cl was 0.5. I thought my swcg was not working, so I set it to super-chlorinate. Seems to be working, I can see it making chlorine.
My cya has been holding at 45-50, now it tests at 0.???
I read about the ammonia test, added 185oz 10%, and I still have 6.5 - 2 hrs later,
so that does not seem to be the answer.
So where did my cya go?
I use all Taylor tests, and everything is fairly fresh.
The guys at Discount salt water pools mentioned phosphates, but that tested 0 also.
Any thoughts?

 

[mknauss]

Is your 45 CYA from two days ago an actual test result from that day?

 

[mepot101]

No, it was 0, but I thought maybe because the cl was at 0.5, that the cya was reading wrong.

 

[mknauss]

When was the last time you actually tested the CYA that you got the 50 ppm result?

 

[mepot101]

The pool has been holding 45-50 since I installed the swcg in May.
Always at 30 when I was using jugs.
It tested 0 for the first time last week maybe? I just couldn't believe it was low. I wish I could have gotten those results when it was at 200+ several years ago. I drained the pool then to lower it.

 

[mepot101]

Just re-tested after the pump shut down, 6.5 cl.
Will test in the am before work, looks like a slam is in the works.

 

[mknauss]

CYA does degrade over time. Also, you live in an area that gets rain to the point the pool can overflow. So there will be some loss from that. I could see your CYA going from 50 to less than 30 (which the test shows as 0) in two or three months. The CYA degrades 10-15% each month during the summer, especially when the pool water temperature is in the upper 80's or warmer.

 

[mepot101]

Just looked at the search results, I guess this is not such a mysterious issue after all. I will add some I have and get some more tomorrow.
Any thoughts on which is better, liquid or granules?

 

[mknauss]

Granules cost about 1/4 that of liquid. Just use the sock method to add them.

 

[mepot101]

Thanks to mknauss and this forum for the help again.
When I first bought this house and pool, I had a continuing algae problem.
Once I found this forum, I realized my issue was cya over 200, and many trips to the pool store was not going to fix my problem.
I guess I got gun shy and didn't want to get too much cya after draining the pool to start over, so I let the cya get too low, and with 2 weeks of Florida sun and no rain or clouds, my SWG could not keep up. I just couldn't believe my cya was gone!?!
Anyways, we're good now with added cya and the week of slamming the pool. I don't know what I would do without the help from this forum.
Great place to be.

 

[mknauss]

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