Adjusting PH


LifeTime Supporter
Apr 12, 2007
When I am fighting algea, do I have to adjust my PH when, according to the test kit it has risen(7.8-8.0) because of the high chlorine. Is this the 'false' reading I am getting or has it really risen? Can I just wait it out until my chlorine level drops back down? Also when you are fighting algea, don't you run out of R-871? I had to reorder more. What do you all do? Thanks Kay


Mod Squad
TFP Expert
Apr 4, 2007
SW Indiana
If your chlorine gets to a reasonable level, test the pH, but I wouldn't make any serious attempts to change it much during an algae battle to avoid overshooting. You do use a lot of chlorine reagents to fight algea if you do it right. You can use the OTO test with distilled water dilution for some of your tests to stretch it out.

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
San Rafael, CA USA
One thing I recommend when one has a pool with high CYA levels (or has yellow/mustard algae) and needs to shock at high FC levels is to lower the pH to 7.2 before shocking with chlorine. This will keep the chlorine more effective even at higher FC when the pH will rise initially (CYA does help buffer the disinfecting chlorine amount, but at very high hypochlorite addition causing high pH this buffering gets overwhelmed). Eventually as the chlorine gets used up, the pH will drop back down, but trying to measure pH when the chlorine is high is almost impossible -- you need to use thiosulfate to eliminate chlorine interference, but doing so makes the pH measurement rise (by roughly 0.1 per thiosulfate drop, though that depends a bit on the FC level).