would a 50 watt heater be good for a 15 gallon tank?just setting up a tropical tank and dont know much,thanks.

depends on the brand.... some heat more water with less power, you would have to read the box ! but normally a 15 gallon is 50w to 100w....

Kev

A 50w heater would be ok, a 100w would be better (as it can quickly put the heat back that is being lost) - The main thing is good water circulation past the heater so the heated water is dispersed through the tank properly. I actually run 2 heaters in my tank for the same reason (plus if one fails, there is a backup).