When I first move Bad Cat into the 300 gallon, he was doing well for the first week, then showed signs of being in distress and was breathing hard. I ran to the store and picked up a much larger aerator and added 2 more stones. Problem solved. I check the water quality once a month, but I am changing water on his tank quite often actually. With there being a non substrate tank even a bit of "debris" at the bottom calls for a quick vacuum. One of the reasons I run 2 Fluval FX6 filters is because I will clean one, leave the second alone. So one is always not disturbed. This has always worked well for me in the past and I did this from when I had large salt water tanks. I found that there were less shock loads to the entire system when doing this.
When Bad Cat moves up a tank size, my plan is to keep the Fluvals, add a third. Then, set up a 55 gallon "bio" filter... basically a 1500 to 2000 GPH pump filtering through 4 "socks" dumping into the 55 gallon tub that has auto level water control. Tub will be filled with positive and neutral bio balls, with an upgraded air blower sending the air to the bottom. I was going to then have a simple over flow back into Bad Cat's tank. If the pump fails, everything just goes to it's natural level. I want it to be dumping its self for water changes. Depending on size of tank.... I was thinking if it exchanged 20 to 30 gallons a day by an over flow into my drain, that should take care of the chore of water changes so often.
