When I had about 6 tanks in one 8'x16' room it wasn't too bad. My brother in law is an electrician, I've done side jobs with him, along with plenty of my own electrical work. Outlet upgrades were no problem, add power strips & a seperate circuit with a gfi breaker & it's all good.
Once I got to around 12 tanks it was pretty well maxxed out. My latest fishroom redo put me up to 16 tanks. This was a little too much for power strips, so I switched from individual power filters on each tank to a centralized air driven system. The only power to each tank now is for the heater, if needed, and the occasional powerhead or canister filter. I light multiple tanks with one flouro fixture, 2 or 3 per light.