Question About Heaters In A 125 Gallon

[Brunell4070]

i have a 6 foot 125 cycling right now, and bought two 300w heaters off of ebay. So, simple question, should i use them both on opposite ends, or is there anyway i can just use 1?
thanks.

 

[erk628]

Not sure about the wattage but I have 150 gallon and I have one on each end that a lot of water to heat.