too much oxygen?

[Great Lakes]

High levels of Co2 will cause a lower ph value.
When you run an air pump, the additional water movement will help precipitate Co2 from your tanks environment, causing a rise in ph.

I did an experiment once. I put an air pump on my 90 gallon in the morning after checking the ph level. Then checked it at night. My ph went from what was a proven rock steady 7.8, to 8.3!

I had been trying to achieve a higher ph for days, so I knew my 7.8 reading was accurate. I had even used three different test kits on it.

It just really drives home how little things can make a large difference at times, and should not be approached lightly.

GL

 

[Bignose]

I would think that the filter return would agitate the surface enough. The air stone can be counterproductive for keeping the CO2 in there for your plants if you want, but I think that if the filter return disrupts the surface, the air stone disruption wont change things much.