I have a 9in silver aro and i want to get him a pond to try and save some money instead of buying a 200g+ tank. I have been told that it is hard to keep the tamp in ponds up, is this true?? and if so how much would it cost to keep warm??? And what size pond would i need for a full grown Aro??? i would prefer an above ground pond if possible. Sorry for all the questions but if u can answer them i will be very gratefull