Will be running a 75 gallon tank prob with 2 HOB filters, should I expect a big jump in the power bill? Any estimates? Will run 2x48 inch lights for 6-8 hours a day as well.
No way. When I was into reptiles I had a room full of them, probably 8 tanks, 3 of which were desert enviroments. With all the heat lamps and UV tubes and ceramic heaters probably like 2000-3000w. My bill went from 130$ to 170$. Im sure runing filters which most are like 30w tops shouldnt even be noticed. Just turn your comp off at night (if you run it 24/7) it should compensate. Change all your lights to CFLs and get more filters and tanks!
Only thing that would show a difference is probably a heater, but probably only when it gets colder and is being used more.