I just recalibrated my PH monitor and the probe was off by .5! I checked the PH with a test kit and it is approximately 6.4, so, a little better than 5.9. I will back off the CO2 and check the other parameters to see if there is a deficiency of some kind. Thank you for the quick response. I turned the air diffuser on and that should help the fish recover. Darrell |