Daily pH cycle

[Bouldereefer]

Naturally the tank pH fluctuates during the day. What is too much fluctuation? My tank goes from 7.8 at night to 8.1 during day. Is this considered a large swing? How do you limit these swings.

 

[mrbluewildcats]

Mine goes from around 8.21 in the morning right before lights come on, to 8.38 right before lights go off. It's been in that range, +/- about .03 for months. My understanding is that pH won't fluctuate much more than that if it's properly buffered, your alkalinity is stable and not too low. There could be other factors that would make pH jump or fall quite a bit, but I think I that's right.

 

[Randy Holmes-Farley]

I think that swing (pH 7.8 to 8.1) is fine.