I live in South Dakota where it gets INSANELY cold, and I don't have a heater for my tank. I have a really good lighting system which makes up for most of that, but at night I shut it off and it doesn't create a problem. My advice would be to get a thermometer first to see where it actually is. I was really surprised that mine stays right around 75 degrees which is a descent temperature. I know people with bigger tanks then mine (I have a 75 gallon) in my same area that have even invested in tank COOLERS because their's get so warm with the lighting. We both have reef systems though, and this is another thing you need to consider with your temperature.