Review on 🐠 Adjustable HITOP Submersible Aquarium Heater: 100W/200W/300W/400W/500W, Suitable for Large Fish Tanks up to 150 Gallons, Includes Sturdy Protective Cover and Thermometer for Optimal Performance by Dina Harvey

I have been using this heater in my coral/aquarium for about a month and a half. So far October-December. In the winter, my house maintains a constant temperature of 68 degrees. I have the sump heater set at 82 degrees, for the past month my tank has held 76-78 degrees. This is a 230 gallon tank with a 50 gallon sump. That's about 270 gallons that a heater will heat every 10 degrees. I'm minus 10 gallons on an incomplete pan. I am very happy with the purchase.