Help with a heater

[alli]

I am a college student and I went out to get a betta fish last night to keep in my dorm. My tank is two gallons and currently has a whisper microfilter in it. My betta seems slow so I went and got a heater that we had from our, much larger, other tank. It is a 100W visi-therm heater. It has temperature control but is it too much wattage? I don't want to hurt the fish and I don't know if it will heat the same way.

[Lion Mom]

That is WAY too much heater for 1 gallons, IMO!!!

I wouldn't go with anything bigger than a 25 watt adjustable heater.

[Alex09]

General rule is 5 watts per gallon. On a 2.5 gal a 25 watt will be sufficient. 100 watts is overkill.

[Feral]

Forgive my intrusion here, but if the heater is regulated properly, all the higher wattage will do that a lower rated one doesn't is to raise the water temp from it's minimum allowable temp to the setting in a shorter time. The wattage/volume recommendation should be thought of as a minimum wattage per gallon, not a max, no? All bets are off of course if the heater has no thermostat regulating it.

[Ajones108]

For one, a 100W heater would be much too big size-wise for a tank that big. For two, I've heard horror stories of higher watt heaters in smaller tanks not properly regulating and killing their fish from a 50 degree spike in a matter of a couple hours. If it were so easy to have a one-size-fits-all heater, everyone would do it.

[dramaqueen]

I wouldn't recommend a 100 watt heater. A 25 watt is much more suitable for a 2 gallon.