Posted: Thu Sep 17, 2009 9:50 am
Turtles are exothermic, meaning they don't make their own body heat. If the room your tank is in is constantly above 78 degrees then I wouldn't worry about a water heater, but otherwise you'll need one.
A UV lamp is installed to replicate the rays of the sun for your indoor turtle. The lamp and heater are in different categories, and in most cases, both are necessary. If it is a financial decision, go with the UV lamp.
-Chris