My above ground 18 foot pool holds 7126 gallons my dip stick and phenol readings last night gave me between 100 and 120 for alcalinity and 7.5 for PH , I add one 3" tablet of stablised chlorine once a week and that seems to do the trick, I also add 60g of coper sulfate to the skimmer as I add the 3" puck ...

I am new to the owning of a pool just got it 1 month ago so I hope the readings I gave you were right...