Help...does my turtles need a lamp?

Red Eared Sliders should be kept in a semi-aquatic amphibious environment (at least a 20 gallon tank filled about halfway with water with rocks above the surface they can rest on). They are reptiles and must manually regulate their blood temperature, so they should be provided with a 50 or 60 watt (don't go any higher) light bulb suspended about a foot above their tank. Make sure you turn it off when its dark outside, and on when its light outside. This way, the turtles can bask in the sun on the rock when they are too cold, and go underwater when they are too hot. Hope I could help.