Newb - high CYA

[Satchamo]

I have a 24000 in ground vinyl lined pool. I’m Indiana where we have only about a 3-4 month swim window. Plan to probably close by mid September. I say this to give context…

I have been treating the pool with TRI Chlor tabs via a Hayward in line chlorinator. I have been putting 6 tabs in every week and keeping it set at 1.5. Up until a week ago it was keeping my free chlorine around 5-7 depending. Problem is (as I’ve learned) my CYA has shot up to around 100 ppm. I know a partial drain and refill is the solution here but with only about a month left of our swimming season my plan was to just deal with it until the off season.

problem is I checked this morning using my Taylor k2005 and I’m now registering 0 chlorine. I noticed the deep end clouding yesterday which is what spurred me to test. So as a precaution I went ahead and shocked with 22 oz of cal hypo shock just to stop any additional bloom until I find out what my maintenance should be for the remaining month.

FYI historically my PH and Alk have been good and in range.

with all this in mind I was reading here and the consensus seems to be liquid chlorine is best to avoid stabilizing issues. Could someone walk me through a plan for the remaining month? Should I turn my chlorinator off and immediately start using liquid chlorine only? If so - how much do I need to add and should it be added daily?

also - I think with 100 ppm of CYA I need to keep my FC a lot higher to keep things in check. What should I aim for there?

happy to provide exact test results if needed!

 

[Texas Splash]

Welcome! Yes. the tabs are the root cause. The high CYA means FC could not keep up resulting in the start of algae (cloudy). To kill and remove algae we follow the SLAM Process. Your K-2005 is missing the FAS-DPD so that you can test FC at higher levels. You'll want to do that SLAM before closing so that you can open up in the spring with clear water.

While a partial drain would seem to stink this time of year, I would still recommend it. Try to get the CYA down to at least 70 so that you can do the SLAM and prepare to close properly. Stick with liquid chlorine on a daily basis. Also see the FC/CYA Levels for proper FC levels.

Pool Care Basics Archives

Your one-stop shop for all things TFP to include: ABCs of Water Chemistry, Recommended Chemicals/Levels, Test Kits, Troubleshooting, and much more!

www.troublefreepool.com

 

[Satchamo]

Thank you for your helpful reply. In order to get down to 70 - I’m assuming drain 1/3 of the pool then refill? Are there any issues that could cause to my liner or special precautions I should take?

 

[Texas Splash]

I’m assuming drain 1/3 of the pool then refill?

Possibly. Depends on your exact (current) CYA). You can safely lower water as long as you don't go too low. I would say 50% (if needed) is plenty safe to keep the walls secure and liner tight.