sudden pH jump followed by way too much acid


Well-known member
Jun 5, 2014
Lake Elsinore, CA
i did a thorough scrubbing of my faux rocks yesterday afternoon, followed by dumping an old gallon of chlorinating liquid into the pool because i needed to just get rid of it (and by old, i mean several years (don't ask, lol) not anywhere near full strength). this morning, my pH had jumped from 7.5 yesterday to 7.9 today (free CL is stable at around 7.0, which gives an idea of how little strength the gallon of chlorine still had).

when i saw the large jump in pH, i figured okay...time for acid. i added way too much acid and way overshot the pH, it's down to 7.0. this leaves me with two questions...

1) am i ok to just let the pH come back up normally like it always does, or do i need to raise it immediately? my pool has a spillover spa that is active any time the pump is running, so it tends to drift up pretty quickly until it gets to 7.5 or so, then it's pretty stable and takes a few days to get from there to 7.8-8.0. i'm adding acid about once a week and had been doing a pretty good job at getting the amount right (to get to 7.5), but today i just somehow went bonkers.

2) are there any other numbers i need to worry about watching, either from the sudden spike in pH or the drastic overshoot on the acid add? i know TA will have dropped, but i also had to add water this morning so i'm hoping it wouldn't be too dramatic a change.

here is my last full set of numbers, from saturday afternoon:

FC: 7.0
CC: 0
PH: 7.5
TA: 70
CH: 925
CYA: 70
Temp: 84.1
Salt: 3600
CSI: 0.05

am i ok to just keep an eye on pH and FC (although with the basic kit i can only see up to 5.0 for FC, the waterguru sense i have in the skimmer gives me a decent idea where i'm at if over 5.0) for the rest of the week like i usually do until my normal full test on saturday, or should i do another full test today to make sure everything else is ok?


Gold Supporter
TFP Guide
Nov 12, 2017
Central California
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I suspect you'll be fine just letting it come up on its own. Or run the spillover until it does. No need to add anything, 7.0 is not that bad, your CSI is just fine. It takes months of way-out-of-range CSI to begin to affect plaster, your CSI is right in the middle of the acceptable range.


Gold Supporter
Jul 8, 2015
you have a SWG.. AND a spill over in the spa.. you will see your pH rise on its own through normal aeration. I don't think you have to worry about your eyeballs melting off or anything.
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