PH question

Then probably very little. Corals respirate at night, reducing O2 and creating CO2. In water, it creates H2CO3, which is an acid. That then has disassociation of a hydrogen atom to decrease pH. So if your coral load is low, you shouldn't see much of a swing.

 

i wouldnt calibrate until you see noticable flucuations after youve have reading for a decent amount of time. just look at your graphs from the past and youll be able to tell if it needs calibration.