Need a bit of advice

[MiaHudy]

Hello,
We are are having a bit of trouble with our pool. It was resurfaced just over a year ago with NPT StoneScapes. It is a small 13,000. gallon kidney shaped pool. I have stuck with my pool guy since the resurfacing and admit to not staying as on top of the water as I should have. I am starting to develop a bit of algae is spots. I have tested my water and this is what I have so far.

PH is 7.5
Free Chlorine is 5.5
Combined is 0
CYA is 80

Pool guy has been adding chlorine/stabilizer tablets weekly and liquid chlorine and acid as needed. I know my CYA is too high, I am not sure what the 0 free chlorine is telling me. Should I drain some water and add fresh to lower CYA, and will this correct the CC issue?

Any advice is much appreciated. I used the TF 100 test kit

 

[Oly]

You are experiencing an algae bloom and need to get it under control. This is due to a low Free Chlorine ppm and a high CYA ppm. Your situation is the result of your reliance on Trichlor tabs. You will need to SLAM your system to control the algae and you will want to replace some of your water to reduce your CYA first. Lots of good information on this site with many folks willing to help. Welcome.

 

[Richard320]

Replacing water will lower CYA. There is no CYA in tap water, so the math is pretty straightforward. If the pool guy persists in using pucks, CYA is going to keep climbing.

I'm not understanding the issue with CC. You have none. That is ideal. Unless you are confusing FC and CC?

Algae is a whole 'nother story. You need to SLAM Process. Soon. A few days at 80 degrees or better and your whole pool will be a green mess. Brush it all away and replace water to get CYA down to something reasonable -- 50 or less. Then follow the SLAM article. If all you have is a few patches of algae, the whole thing should only take a few days and less than a truckload of bleach. Don't be tempted by any of the miracle products at the pool store. Some of them contain Monopersulfate. That stuff will mess with your CC tests for a long long time afterwards. Some have Bromine. Use it once and you have just converted yours to a Bromine pool. And algaecides work better as a preventative than a cure in the same way that Lysol stops the spread of germs but drinking it won't cure a cold. Stick with liquid chlorine.

 

[MiaHudy]

Thanks very much, any suggestion on what percentage of water to replace to get the CYA down to where is should be?

 

[Richard320]

Thanks very much, any suggestion on what percentage of water to replace to get the CYA down to where is should be?

Roughly 40%. 60% of 80 CYA is 48. That'll test as 50. It's not really possible to measure 40% precisely, either. If in doubt, drain a little more. It's super easy to add more CYA.

 

[MiaHudy]

Thanks for the help!