My pH is creeping up over a few days time. I'll take it down to 7.5-7.6 using MA/pool math and verify with the TF-100 test kit 6-8 hours later (all good), and a few days later it's looking like 8.0+.
Readings today were
FC = 3.5 at 0700
OCLT = 0 (measured last night at 1950)
TA = 90 (has been consistent for a long time)
PH = 7.5 (after about 30 oz MA last night)
CYA = 40
Borates= 23 (calculated from a virgin pool refill from municipal water x 7 76 oz boxes of Borax)
Water is crystal clear...can read a dime date at the bottom of the deep end. Really never been better.
Using 8.25% wAL mART bleach and Cal Hypo....alternating.
I am running a small PVC fountain that connects to the unused vac return line. It shoots about 10 fine streams of water up about 6 feet high and lands in center of pool at deep end. I always read that aeration will not cause pool PH to go from 7.0-7.2 only as high as 7.5 (this when you need to lower TA)......Since wife and kids like the fountain...I left it on thinking if it was t 7.5 it would stay there.
Should I disable it?
I do have an elevated spa overflow that is about 2 feet wide. The ledge spillway is 2" out over the pool...so there is some aeration there as opposed to it trickling down the spa wall in the pool. I have to circulate some water thru the spa to keep it from growing Algae, so stopping that it seems is not an option.
Thoughts? What other reasons would cause PH to go up in 2-3 days time and time again?