Like the others suggested, I have that same heater (marineland 10w...I think I was the agressor on that heater push! XD) BUT! Be warned! A two is a smidge hard to heat at times, due to the size.
I highly HIGHLY (if you dont already) advise you to get a good, quality suction cup thermometer to monitor the temp, in case it gets a bit too warm. It likes to heat my 1.5 to 84 and the same with my 5 (in a warm room) :B