I was running two TopFin heaters on my 125 gallon tank, and all of a sudden i put my hand in the tank one day to do a water change and it was 73 degrees when i had my heaters set at 84. No idea what happened, but luckily i had a bunch of little heaters laying around so i replaced those heaters with three little ones that will hopefully do the job for the time being. I want to buy the best heater possible so that this doesn't happen again.. What heater do I get for the 125? and will it have enough watts or will i have to buy two?