Is a 50 watt heater big enough for a 30 gallon tank?

Question

If not what watt heater do I need? Thanks.

Answer 1

To small it will work overtime, you want around 150 watts for a 30 gallon tank.  

Answer 2

The rule of thumb is 3-5 watts of heater power for each gallon of water in the tank.  So you should have 100-150 watts of heater.  A 50 watt is not big enough for a 30g tank.  

I would suggest two 75 watt heaters, one at each end of the tank.  This will keep you from having a cool area at one end of the tank and a warm area at the other.  

Submersible heaters are the best because the heated water will rise and create its' own flow of warm water.