I have a submersible adjustable heater from Petco in my tank, 50watt. It works very well and keeps the water at a good 80 degrees. There's a nice one made by Hydor.

 

Hydor and Elite heaters are recommended highly. But a member here stated that when the Elite's "sphere" on the top of it gets all slimy and mucus shows up if that part is in the water. Get adjustable heaters and stay away from Top Fin ones, those are known to mess up. Don't get preset heaters either, they tend to under heat or even overheat.

 

Hydor Theo adjustable. I have the 25 watt for both of my 3 gallons but not sure what they are rated for. Nice quality heater and I am very happy with them.

This is the one I have: http://www.amazon.com/Hydor-THEO-Su.../dp/B0006JLPG8/ref=sr_1_1?ie=UTF8&qid=1348187407&sr=8-1&keywords=hydor+theo+25w

 

I second the hydor heater!

 

Thank you everyone! What watt would you recommend for a 10 gal? 25?

 

For 10 gallon, I think a 50watt would be good.

 

Alright, thanks =)

 

50 watts is a great wattage for a 10 gallon tank.
I reccomend Via Aqua heaters because theyre adjustable & have a thermostat, allowing you to keep the tank at the desired temperature, unlike preset ones. Theyre also super affordable and worked great for me.

http://www.amazon.com/ViaAqua-50-Watt-Submersible-Built-In-Thermostat/dp/B005440HLO

 

Ooo! That looks great! Do you think Petco or Petsmart carry it? If not then I could difinetly order via Amazon.

 

Yeah, I went to Petco and Petsmart for supplies, neither carry them.

Thank you so much!