CYA question

[Jkmccoy]

We had off the chart CYA when we opened the pool in May. Through the help of this group and A LOT of draining and refilling we got the CYA to 70 and started SLAMMING the pool. Since then we have enjoyed a very easy summer of pool maintenance. I did not check my CYA all summer since chlorine and ph levels were fine, but we are getting ready to close and I wanted to be sure of CYA level so I knew where to bring the chlorine to. Our CYA is now at 30. Is that possible? We have had rain and we have 3 kids and their friends using the pool all summer so there is splash out. We have had to refill a few times to bring back up to skimmer level, but it seems like that wouldn't be enough to bring the CYA down 40 points. Thoughts?

 

[BasicTek]

CYA will drop about 5 a month by itself, rain and splash out can make it drop even faster than that so it sounds about right. I've lost about 20 from June to August and another 20 from the hurricane Irma

 

[JoyfulNoise]

I'm in a hot & dry climate and I have seen my CYA decrease by as much as 20ppm in 1-1/2 months. CYA does get oxidized by chlorine and UV so it is possible to lose it at a measurable rate.

 

[Jkmccoy]

So should I add CYA before I close it or leave it and adjust next season?

 

[tim5055]

I would,wait until you open in the spring to add CYA. But, if your CYA dropped have you checked CH?

 

[Harbinger of Fun]

I have this question too. I last tested CYA in late July at 60ppm. I bought new R13 from the store (Taylor brand this time) and now my CYA is apparently below 20pppm?!? We did have Irma here where I drained twice.

FC: 9
CC: 0
CH: 100
TA: 50
pH: 7.4
Salt: 3200ppm
CYA: >0 but <20