CYA levels really high, how to lower?


Mar 30, 2017
Greenville, NC
I'm new to the forum so I will give a brief rundown on what I got going on. I have a 24' round above ground pool (approx. 13.500 gallons). I opened it up last weekend and it had gone really green for some reason. I have always used the 3" chlorine tabs and pool essentials 1lb bag shock and had great success with it for several years. Well, I shocked it good with about 7 pounds of shock and went ahead and through 3 tabs in the floater. I gave a day or 2 and it turned back blue but was very cloudy. I then checked the TA and PH and there is no TA at all and the PH is 6.8. I only have the Taylor K-1004 which does not test CYA. I ended up carrying a water sample in yesterday and they just called and verified I had no alkalinity and low PH but my CYA was 151!!!! I really want to follow the BBB method this season and was looking for advice on what to tackle first. I assume I need to get the CYA down before I try and add the baking soda to get my TA up. Is my only option in getting the CYA down to drain half the pool and start from there? I have already spent more on chemicals than I want to and come up being a waste because everything keeps canceling itself out with other levels being so far off. What is the best step by step to overcome my issues?



TFP Expert
LifeTime Supporter
In The Industry
Jun 12, 2009
NW Ohio
Welcome to TFP!

As much as I don't trust pool store results, the tend to not be too bad on pH and TA and if your TA is zero then your pH is well below 6.8. That is something that needs corrected right away as it can cause some damage to your pool and equipment.

As for CYA, well I don't trust a pool store CYA measurement at all but assuming it is high then the only remedy is to replace water. Assuming you have a decent TA in your fill water and you are going to start a partial water replacement right away then you can get away with draining part of your water now and then adjusting your TA after you get some new water in. Don't let the TA issue wait though, it is important to get that fixed now. Just FYI, this is likely because of the tablets slowly bleeding your TA away, they are highly acidic. Pull that floater out, it is doing nothing but hurting the pool at this point.

To properly manage your pool using TFPC you need accurate testing. To accomplish that you need to get your hands on an appropriate test kit, either the k-2006 or the TF-100. This will help you cut ties with the pool store and get some trustworthy results to base your pool care on and avoid wasting more money.

After you get one of those on order you can do a bit of quick reading to familiarize yourself with the terms we will be using to help you going forward:
Pool School - ABCs of Pool Water Chemistry
Pool School - Chlorine / CYA Chart
Pool School - SLAM - Shock Level And Maintain

This might all seem a bit overwhelming at first, but remember this isn't just a quick fix. This is a change in the way you care for your pool that will help you avoid falling in to situations like this and keep your water clear and sanitary on an ongoing basis.

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