Significant PH rise after heavy rain?


Active member
Mar 17, 2017
League City, TX
We just finished up with a couple of days of heavy rain which brought the pool level up around four inches. I started my SWG on a shock cycle yesterday . I did a full set of TF-100 tests today (minus CYA which will be a whole other thread on that chemistry question) and got mostly what I expected given dilution. The surprise was PH which went from 7.5 to somewhere above 8.2 in that timeframe. I would have expected it to drop with rain.

Any insight?


In The Industry
Jun 20, 2016
Two things:

1. Aeration from a heavy rain can raise pH, though I doubt that significantly.

2. Most likely culprit is the super chlorinate mode you turned on. pH rise from an active salt cell is significant, especially when the cell is producing chlorine 100% of the pump run time as is the case during "shock" mode.

- - - Updated - - -

By the way, what was the alkalinity out of curiousity?


Bronze Supporter
Dec 22, 2016
Arlington, Texas
[LifeHack]In order to extend the life of your cell, any time you need to raise FC quickly, just add bleach. A cell is best utilized to maintain an FC level.[\LifeHack]


TFP Expert
LifeTime Supporter
Jun 7, 2011
Midland TX
It's Aeration from both Chris. Also two days time, and higher TA. It all adds up. A little more than I would guess, but there are always surprises. Could be a little testing variation in there too, but no worries either way. I agree that having some fresh bleach around is never a bad thing when you need a little boost.
Thread starter Other Threads of Interest Forum Replies Date
C Testing and Balancing Your Water 3
P Testing and Balancing Your Water 10

Other Threads of Interest