two heaters
 

I have a 45 gallon fowlr, and I think my lighting alone will keep the tank around 76 or 78 during day time. However, at night, when the lights are off, I will need some other external heat source. Would two 25 watt heaters around the bottom of the tank on opposite sides suffice for heat at night? I wouldnt expect the temp to change more than 2 degrees over 8 or 9 hours with no light, especially with the heaters in there. What do you think?

the general rule of thumb is 3wattsxgallons. You should need 135watts. You tank should be more like 80-81F and not 76. Unless you get a fish from the part of the ocean that has lower temps, you'll want to keep it close to the general range. 2x60watt heaters should be fine for the tank.

Okay, thanks for the reply. Can you recommend any good books on general to advanced knowledge on sw aquariums? I think a book would be a nice investment to make in a hobby such as this.