Loss of CYA over Summer

[danielduerr]

I had 75 ppm of CYA in March and tested it again yesterday to find it was <15 ppm using Taylor K-2006 kit. I am confident in my test ability, but don't normally test CYA due to historical experience that once stable, it doesn't go away without water change. Like the others here, I am confident I do not have a leak or abnormal loss of water. I opened the pool on 4/15 and have kept it at 90 all summer, with one accidental day where my son turned it up to 100 (solar got us to 99 by the time I caught it). So I am thinking it may be heat/temp related as suggested earlier here?

 

[mknauss]

Welcome to the forum!
CYA does degrade some during the summer months. Mostly due to elevated water temperatures. Splash out, backwashing/filter cleaning, etc, can have an effect. Also, the testing method, at best, is =/- 10 ppm.

Add 20 ppm of CYA granules using the sock method. Once dissolved, test the CYA after 24 hours.

I suggest you read ABC's of Pool Water Chemistry.

 

[danielduerr]

Thanks @mknauss! I've been following your ABCs since pool construction in 2016 but this is my first post. Love you guys and have turned a number of fellow pool owners on to your fool-proof methods.

We admittedly keep our pool on the warmer side, so it makes sense we'd see an effect here. And agreed on the variance with the test, particularly since I have good eyesight and a little light can have a dramatic effect on the dot. I tested CYA three times yesterday using 3 different reagents in my stockpile just to make sure the result was consistent.

I found the sock/granule method a bit tedious to get to the CYA levels I was after, so I switched to using liquid form stabilizer, specifically the Natural Chemistry product on Amazon.com. I understand either solid or liquid form is the same thing. But do you think there might be a difference in how I dosed the liquid form that might have led to a faster dissipation of the CYA?

 

[mknauss]

I have never used the liquid. I would think it is the same as solid as to resulting CYA levels.

I have heard on this forum that you need to use the entire bottle of liquid when you use it. The particulates settle in the bottle and must be washed out.

I suggest you monitor your CYA each month during swim season. Add via trichlor if you wish. I do that when my CYA falls. Which it does, normally ~10 ppm per month from May to October.

 

[danielduerr]

Ok, thank you. Great advice. I think at the end of the day, my lesson here is that CYA actually does dissipate and I need to monitor it more frequently like you say. Good to know!

 

[Katodude]

Also the warmer your water the faster CYA will dissolve with the sock method. If you water is 90 or above it will dissolve very quickly in front of a return. I order a box of 25lb of CYA almost yearly from Amazon, best price per lb I can find.

 

[djdonte]

I’ve found myself adding CYA maybe once every month or once every other month in the summer. I only test CYA every few weeks. When this happens, I go back to using trichlor pucks with my in line chlorinator to sanitize for a week or so and check CYA again. I was dropping from 50 to 30ish and a week with pucks would get me back where I want, except for one tropical storm we had. Either way I like it because it gives me a break from buying/adding liquid chlorine. When I run out of pucks, I’m not sure if I will buy more pucks or try the sock with powdered CYA.

 

[KDpoolguy]

You all remind me I haven’t tested my CYA in almost 2 months. I always managed it with pucks, but now having a SWCG I’ve learned the skimmer-sock method. It doesn’t work well for me as last time it took weeks to dissolve until I’d go and shake it once a day.

 

[YippeeSkippy]

Pools that get a lot of rain,and have overflow and lots of splashout, along with backwashing the filter occasionally do tend to lose more CYA than others. It also just degrades normally at a small pace. Best to check at least monthly to avoid surprises.

 

[duraleigh]

Best to check at least monthly to avoid surprises.

A BIG plus one to that!