I have had my turtle for 13 years. I had him in a 20 gallon tank for the majority of his life without a heater because the water was never really cold. Now that I have him in a 80 gallon tank the water is much colder. I'm afraid if I introduce a heater to him he won't adjust well to it. Will it be safe to introduce one now?
Also I looked into various kinds and some people have reported the water over heating leading to death. If I need a heater does anyone suggest a heater that is known to work well and has a good warranty?