I am beginning to think that I would like to set up a turtle tank. I have a 55 that is the planned tank. The turtles would have access to dry land and a basking lamp in the tank. I would like to have a red-eared slider and a common musk turtle as the inhabitants (both males). I might also have some goldfish in there to help keep the tank clean. I know turtles need sunlight to stay healthy but I would like to avoid spending the extra money on a fixture with UV lighting. If I were to place the tank near a window that recieves indirect sunlight about 5 hours during the day. Is this enouph to keep them healthy?