Thanks VaughnH...! I guess pushing the pH further down wont harm the fish...? I'll take a sample from the tank tonight so I can see how low I must push the pH to get a decent co2. I calibrated the probe today with fresh buffer and it was off with 0,1 so the pH is actually 6,5 and KH 3,5 (I counted Tetra drops in 10ml samplewater instead of 5ml to get more accurate KH)

I have five Clown Loaches and for Pearl Gouramis. It looks like they prefer a pH at 6,4 decreased by tannin instead of 6,5 by Co2. The Clowns have been more active and full of "jokes" all day, and tonight they waited for the wafers at the front of the tank before the lights went out. Usually they wont eat for hours after the lights (and the co2) shut off.

As things are right now the tank runs like a non-co2 tank, so would it hurt to slowly increase the co2 by the tannin removement caused by weekly 50% waterchanges? I've been fighting some real bad BBA before I got my co2 stable at 30-35ppm.

There was some pearling a few hours before the lights went out.

Vidar