Hey Ben I posted this somewhere else bc I couldn't find my way back but here goes
I think I am having the same problem. I am new to the forum ( well posting anyways) I have a 35k+ gallon L shape boy cya is 65-70 and I can't keep the CL up I have used 45 gallons of cheap bleach in 3 days. Readings are CL drops from 5 to 0 overnight. Ph is going between 6.5 & 7.2 I have used 6 boxes borax in the last week also. I have 3" chlorinating tabs running constantly thru a chlorinator. Alk is 50. Using 6 way hth kit & strips. Strips say stabilizer is low but hth says high? Very confused. I am having surgery Wednesday & need to get this in order any help is appreciated.

Hth 6 way
CL 0 just added 5 gallons bleach tested its bright yellow after 1 hour
Ph 7.2
Alk 70
Cya maybe 65 Can't test anymore I ran out of drops. ( the bottles is not proportionate)

Thanks so much for having this forum I am going crazy & everybody is driving me crazy asking when it's going to be ready