okay if I have a 180 gallon tank in a place where the air temp is usually about 65 degrees F how many watts do my heater(s) need to be to keep the temp at between 76-80 degrees?
Is it an air-conditioned room? well, whether or not it is, the heater do there job right - but you should check the packages. For a 180 gallon I believe you would need 2 300Watt heaters and 1 150W heater. Which is, like said by basinjib, 750W.
Lol I heat my 30 gal with one 300w heater, looking at changing that very soon as I don't wanna risk overcooking the fish.... shame the heaters going to have to go in a box for a couple of years till I can afford a tank big enough for the heater
Well I use 2 x 300w heaters for my 170l tank, but it's in an unheated garage with temperatures starting to hit freezing. When it's warmer I'll only run 1 of them.