I am going to have a pond (600 gallons at least) with a texas cichlid and a pumpkinseed sunfish. I am moving to the Houston area so the temperature outside will rarely drop below 60 and even then it will . Will I need to heat the water or will it be fine if they go through the colder temperature for 3 months? And if I need to heat the water do you have any suggestions for what I should use to do so?