Thanks for the replies. Yeah that's my intention to have auto water changes. I think we revised our list to the 500 cichla, 300 jag and other cichlids, 180 discus, angelfish, and a few assorted tropicals, and a 55 gallon saltwater. We may upgrade the 55 if it seemed feasible someday. I have no desire to overstock, because I want my fish to be as happy and healthy as possible.
I know we had discussed the electricity usage. We live in Kansas now, but are probably moving to Georgia before we do this. My wife is from there, so she wants to move back home. Where we live now with the 210 we had, a 55, a 54, and a 92 running power usage seems negligible. It might actually cost 50 a month. I never really paid attention or attempted figuring. Hopefully it won't be too much more there.
I know we're going to start with the 180 and 300 and then consider the others if it seems ok.