Co2 and PH

[Billybeau1]

Randy, this has been bugging me for a while. I just can't get this in my head.

If excessive Co2 lowers PH, then why is the PH of my tank the highest at night when we've been home burning candles and breathing and such. At lights out I'm at 8.2 and change. In the morning I'm at 8.12 to 8.15

I would think it would be the opposite.

 

[Randy Holmes-Farley]

The pH and CO2 levels will be driven to a large extent by things happening in the tank itself. During the daylight hours, photosynthesis uses up CO2, driving up the pH. At night, respiration produces CO2, reducing pH. That effect predominates in most aquaria, even if people come and go at intervals counter to that.

 

[Billybeau1]

Oh I see. Thanks I can live with a .05 swing.

P.S. I dont think my fish would like me to keep the lights on all night

 

[Randy Holmes-Farley]

No, they might get cranky.