[Question in regard to heating.]

It would be for the least amount of energy used

[Question in regard to heating.]

I have a 75 gallon aquarium that is heated through a oase biomaster canister filter. I was also considering using two 150 watt heaters on each side of the aquarium instead. I am wanting to have it where the heaters wont constantly have to run. So the question is a heater that is ran by a canister filter more efficient or is having two heaters inside of the aquarium on opposite ends more efficient?