Welcome to the forum!
CYA does not disappear quickly. It mostly is removed only when you take the water in the pool out and replace with fresh water. And that does NOT include evaporation.
How did you test for the CYA level?
I suggest you read
ABC's of Pool Water Chemistry and consider reviewing the entire
Pool School eBook.
I use
Mel,
How many bags of "shock" do you throw in your pool each week/month???
Jim R.
Thanks for the questions. I appreciate your taking the time to consider my issues.
I have had this p
ool for 15 years and never had this particular problem.
My pool gets little use. It is located very close to the Pacific Ocean. Until last October, I have been able to maintain my chemicals using PoolMath suggestions. Primarily used 3-inch trichlor tablets, muriatic acid and algaecide. I used to have to raise my CYA using the powder in a sock method. But now it is very high.
I have used In The Swim Lithium Shock occasionally, maybe once every 4 weeks but always after a good rain and at the first sign of algae. Two one-pound bags in my 16,000 gallons. I am ready to order more lithium shock but see it has been discontinued.
I use Aquacheck7 test strips, purchased recently, expiring December 2020, kept in a cool dark place.
Right now I'm having trouble keeping my TC and FC up. I shocked April 18, but keep getting very low chlorine readings. I've added one gallon Clorox April 21 and April 23. Still very low, TC at 1, FC at .5. Although using Blue Devil OTO test drops I do show 1.0 Chlorine reading.
Here are my latest readings using the AquaCheck 7 strips:
Total hardness: 1000
Total Chlorine: 1
Free Chlorine: .5
PH: 8
TA: 240
CYA: 200
I have added 3 liters of muriatic acid slowly over the past 10 days.
I replace evaporated water (about 1/4 inch a day) with well water from our private neighborhood well.
I buy my Clorox at Costco in Cabo San Lucas and don't find the word "Cloromax" anywhere on the label.
I know replacing water is the suggested way to get CLA down, but water here in the desert is in short supply and extremely expensive, if you can even get a large quantity at one time. Plus I've been told not to empty a vinyl liner pool as the liner is probably brittle now. I replaced the liner after Hurricane Odile in 2014. I'm hoping there is another way to get in balance.
Thank you all for any help with this!