It's been three weeks since my last water change and during the last week my PH has gone up out of the color range to be brought down by two drops of Taylor acid base to 7.6. I check it two hours after I add PH down, 24 hours after and it is OK, after 48 hours it goes right back up, have done this three times to make sure I am not doing something wrong but get same results. Everything else is in line.
Any ideas why this is happening, could PH down chemicals be off or is there something I am doing wrong, I have done a number of changes of water and have never had to touch my water balance except for minor changes, nothing like this.
Would doing another water change be the answer? I pump my water out and 350 gallons empty in 18 minutes so to dump the water in no problem, filling and heating take the time and money.