Chlorine isn’t holding like it should be?

Aug 7, 2018
91
Canonsburg/PA
Pool Size
22000
Surface
Vinyl
Chlorine
Liquid Chlorine
Sunday June 5, 2022
FC- 3.5
Added chlorine to bring it to 6

Reading as of yesterday afternoon
Tuesday June 7, 2022
FC-.5
TA-77
pH- 7.5
CYA- 30/40(it’s in between)
I put a gallon of chlorine in

Today June 8, 2022
FC-1

I slammed my pool at the start this year and passed all three tests. That finished approximately May 14, 2022. Now I have just been maintaining. Everything has been good. Pool has needed about 1 gallon every other day to keep where needed. Which is the normal for me. Yesterday tested on the every other day and my chlorine was .5. So I was like whoa what is going on but added a gallon. Today I tested and it dropped again to 1. What do you think is going on? Is it because it dropped so low?
Only other things this year is I have tried to raise my CYA 10ppm, 3 different times. I added what the pool math said to raise it 10 and it did go from 30 to 40 but then went back to 30 about a week later so I added again and it stayed between 30/40. So I added one more time about another week later and same thing. I purposely gave a week to make sure it was at 30/40.

Any thoughts or suggestions?
 
You passed an OCLT so that should rule-out any algae concerns for now. From this point forward (FC of 11.5) monitor for the next 24 hrs. If you lose more than 4 ppm by this time tomorrow, increase your CYA by 10 ppm.

At no point in the future let your FC fall below 3 ppm if you can help it. If it does, increase it to about 8 right away and run another OCLT. Have a great weekend. :swim:
 
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