Hey TFPC community,
Thanks for the great site and helpful info! I moved into a house with an in-ground pool/spa with spillover a while back. Because of this site, I transitioned the pool this summer to manual dosing of 10% liquid chlorine. After years of trichlor tabs for this pool, the CYA had reached the 160 range. I did a few partial water changes over the summer and brought CYA down to 60. I used to have a pH that went down due to the trichlor tabs. Not any more. So, that's where my question comes in. pH is constantly creeping up. I am routinely bringing the pH down from 7.8 to 7.4 once to twice per week. My understanding is that the liquid chlorine has a net zero effect on pH, so long term (over a week) this should not be the cause of the pH increasing.
- Is the aeration from the spillover (my only source of every day aeration) enough to move the pH up this fast? (is it normal to add acid like this twice per week?)
- Is there a way to make the pH more stable?
Here is some info about the pool and my testing
17,000 gal in-ground plaster pool with spa and spillover
FC kept in 4-7 range
CC near zero
currently the daily FC replacement dose is around 2.0
I most often use a LaMotte ColorQ 2056 test kit - I also use a Taylor k-2006 (C) kit. I've recently had a bit of an offset between the two kits for pH (LaMotte might read 7.6 when Taylor reads 7.8). This morning, however, they both seemed to agree on 7.4 after adding acid to the pool.
thanks for your help!