Confused about CYA

[circlenranch]

OK, I am confused about CYA. I thought CYA stabilizes chlorine, so how come you have to use more chlorine if you have a higher CYA? The CYA in my pool right now is 0 and the recommended amount is 30-50, so if I up the CYA level then I will have to up the chlorine level also?

[Watermom]

Yes, with more cya you will have to up your chlorine level. But, in a pool with no cya, it is impossible to keep any chlorine in the pool and thus your pool isn't sanitized and is an algae fest waiting to happen. See the sticky about the "Best Guess" chart at the top of the chlorinating chemicals forum.

[circlenranch]

But why do you have to use more chlorine if CYA is supposed to stabilize it? It would seem to me that since my CYA is 0, I should have to keep dumping chlorine in the pool, but the Best Guess chart says 1-3 ppm to maintain a clear pool? So if I up my CYA that means I will have to keep adding more chlorine to maintain? I doesn't make any sense to me

[aylad]

The purpose behind the CYA is keep the sun from consuming the chlorine, giving the chlorine a chance to work on what's in your pool. If you have an indoor pool, you don't need CYA. If it's outdoor, and you have any sun on it, then the sun will consume what Cl you have, leaving none in the pool to work on your water. The CYA keeps the sun from consuming it all, but it also makes the Cl less aggressive toward "goo" in your pool, requiring more of the Cl to do the same job.

Janet

[circlenranch]

"The CYA keeps the sun from consuming it all, but it also makes the Cl less aggressive toward "goo" in your pool, requiring more of the Cl to do the same job."

Ah, now I understand. Thanks aylad!

[karrde97]

I had the same confusion. My pool is in sunlight all day and I'm putting in 2-3 Quarts a night(On sunny days. Nothing on cloudy/rainy days). My CYA=40. Now it makes sense.

A question I have is that the Best Guess Chart is based on FC. Does this mean I have to test my FC every day? I don't have enough powder(PS234) to do this all summer. I will have to buy more. I've been using the PS200 to check for CL & pH daily.

[JohnT]

A question I have is that the Best Guess Chart is based on FC. Does this mean I have to test my FC every day? I don't have enough powder(PS234) to do this all summer. I will have to buy more. I've been using the PS200 to check for CL & pH daily.

It is intended that you do the daily check with the PS200. I only use the powder on Saturdays and if I have reason to suspect a problem.

[aylad]

It's a good idea to check it daily until you get a feel for your pool--I can pretty much predict what mine's going to be from day to day based on my average daily chlorine loss.

Janet

[karrde97]

The trend I'm starting to notice is that on sunny days I need to add 2-3 quarts. Rainy/cloudy days 0-1quart.

Another question...Has somebody done a cost comparison of bleach versus chlorine? I'm curious since I'm putting so much bleach in per week.

[JohnT]

Has somebody done a cost comparison of bleach versus chlorine? I'm curious since I'm putting so much bleach in per week.

Bleach IS chlorine, specifically sodium hypochlorite. Cost isn't the issue. Bleach, either as laundry bleach or the stuff you buy at the poolstore in higher concentration is the only thing that doesn't add something that will cause you trouble a few seasons down the road. Trichlor and dichlor add CYA. Cal-hypo adds calcium.