Is that the range of temps in the location of the tank wo the heater? Consider the temp of where your tank is located. If it runs 75-82, with very little temperature variations, (for instance the tank stays at 76-77 degrees or 80-81 degrees) then no, you may not even need a heater at all. If, however, there is a big range, then when it's cold you will need the heater, and when its actually 87 degrees, then you may need a chiller.