Will increased temp cause increased ph?

Fishfinder · Apr 29, 2018

is that possible? I'm trying to determine if my ph probe is bad or if my tank being warmer some days is causing an increase in ph. Will a higher temp cause increased growth leading to higher ph?

The difference isn't huge but I've noticed if the tank is running about 1.5 degrees warmer my ph is .1-.15 higher

Bad probe or true possibility?

Crabs McJones · Apr 29, 2018

Increased temperatures will slightly decrease ph. But not enough that you'd be able to detect with a test kit. Not sure about a ph probe though.

Fishfinder · Apr 30, 2018

increase temp will decrease ph? why is that?

Crabs McJones · Apr 30, 2018

Fishfinder said:
increase temp will decrease ph? why is that?

I'm going to see if @Randy Holmes-Farley can chime in with a better answer, but I believe that PH decreases due to the increased activity of the hydrogen ion.

Randy Holmes-Farley · Apr 30, 2018

I think this is a very complex question and depends on what you are really asking (response of a pH electrode vs actual change in pH, is the tank aerated after the temp change, what temperature are you referring to (tank water, room air, both, etc.).

A 1.5 degree temp change in the water won't cause the effect your report for any physical chemistry reason. I doubt it impacts the biology much either, at least in a way that alters pH that much.

Did you measure at exactly the same time of day (it changes day to night).

Most likely, the effect you are seeing may relate to your home air CO2 levels, which on warmer days may be lower than cooler days if windows are open more, etc.

Or it could just be pH drift and not an actual change.

If the tank water temp is changing, then there is an effect and some pH measurement devices account for the effect of temp on a pH electrode which is not a pH change). Many devices do not correct for these changes, but the effect is not large for a few degrees.