super-awesome, thanks for the advice. 12-2 wire (if copper) will carry 20 amps (according to my sources) and it's only $75 for 250ft, so I'm ok with that. I'm breaking them up into multiple circuits as much for emergency as anything else. if something causes one circuit to pop, it's unlikely to be on the one with just the return pump and heaters...that way I keep them running well. The lights and skimmer are 2nd most important (I think?) so they will also get their own, for the same reason. we're having an electrician swap out or (very outdated and not-to-code) breaker panel anyways, so cost of the circuit is negligable, and the wire is cheap enough.
does that sound like a good priority list? return/heater as most important, lighting/skimmer as 2nd?
also, It's a 90 gallon now...hoping a mod can change the title. not that it changes your point about the low elec reqs though