High CYA

by Gary

I just got back Lelie's with water analysis. I have a 10000 gallon pool, all tests normal except CYA acid was at 200. Been having problems with really fast chlorine loss and small amounts of yellow algae on sides of pool. I had same test last week and my phosphates were 2500+ and my CYA was 100. I shocked my pool and was gone for 6 days and upon return tested phosphates myself and there were none so I went back today and got retested and CYA was 200 and phosphates were around 100. Is this possible?

I did not treat for phosphates. I understand that shocking with chlorine granules (chlor brite) and using the tablets increase CYA. Is there a better option? We live in a hot climate and advised not to drain pool until after summer if we need to do that. Is the Bio Active product to reduce CYA an effective product? We are in a drought area so would rather not drain if I don't have to. I am ordering the Taylor test kit and might get another test from Leslie's in a couple weeks. Thanks for your response!

Hi Gary

After taking care of pools for the last 17+ years, having a site for 7 years, and answering about 2300 questions, I see patterns develop. The kind of info. you provided, along with the amount and how it was structured, gives me reason to believe you already know what happened, how it happened, what's happening now, and what will happen. I'll just connect some of the dots.

Don't worry about the phosphates. They're food for algae but are basically a non-issue with pool chemistry. Chlor Brite is liquid chlorine while Chlor Brite II is sodium dichlor. Just wanted to clarify that. You already know that using stabilized chlorine will increase the CYA. Honestly, there's no better long-term solution to reducing the CYA than a drain/refill. Once the CYA is in the best way to reduce it is by dilution.

BioActive has received some good reviews and it seems to be effective. The issue I have is once you start using it you'll need to continue its use. It basically binds up the CYA. If you stop using it the CYA will go back to the original level. 8 oz. for $60 is the price and take up to 10 - 14 days to be effective. I talked to a rep from the company and I had to pry information out of him. Not a good start with that.

Some pools that are opened in Spring can see their CYA decrease. BioActive could possibly be used in a water restricted or drought areas but be mindful that once you start, you can't stop, or else.


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