Too much power for a 12G?

[intarsiabox]

If you have the 150W 6-8" above the tank it shouldn't be too bad. If the temps do start getting high have a fan blowing across the tank between the fan and water. An auto top off unit may also be required as it doesn't take long to evaporate enough water from a 12g tank to change the salinity on hot days.

[kylejordan]

I've got a 150watt over my 18 gallon... and I can't keep my heat up enough with my little heater... seems to have no effect what so ever temperature wise. its about 6" above the surface of the water.