Hi everyone - Just got my first pressurized CO2 setup. I had a DIY CO2 setup before that. I set the system up to go at about 3 bubbles per second this morning. I came home around noon (so the CO2 had been running for about 4 hours), and found that all of my cardinal tetras were near the surface of the water gasping. They're usually in the middle of the tank, vertically. I also found that my three adult clown loaches were practically motionless, and barely breathing at the bottom of the tank. They also weren't in their usual 'cave' hiding spot, they were out in front - not sure why. Anyway, I immediately shut off all CO2 and did a 75% water change. The cardinal tetras seem to have rebounded quickly. One of the clown loaches stopped moving completely (no mouth or gill movement) so I nudged him gently -- he moved a bit, but then settled back down on the floor of the tank. Another minute later and he started moving his mouth/gills again. A number of questions -- 1- Are my fish going to be ok? 2- I've heard clown loaches are considered to be more 'difficult' fish to care for. I've never, ever had any problems with mine. Could it be that maybe they're more sensitive to high levels of CO2 than other fish? 3- Did I add too much CO2 too soon? I'm guessing I did. If that's the case, how should I start my pressurized setup? One bubble per second or less for a week - then add more gradually? 4- Any other tips? Is there anything else I should do for my fish? Should I do another water change this evening? Should I keep poking the loaches to try to get them to swim around more and keep moving? My wife will have my balls if I kill the clown loaches. She loves those guys. Thanks for the help, as always!