Review on Encompass All Advanced 100W Digital Aquarium Heater - Thermometer & Wireless Controller | Product Certification Included by Amy Johnson

The temperature gauge has a nice anti-glare display, it takes a long time to heat a 20 gallon tank to 15 degrees above room temperature. It takes an unusual amount of water to turn on the thermostat. And generally about 5 degrees on the high side. Works well as long as you have high flow against the unit and adjust it and then measure the temperature of the water in the tank to estimate the difference between the actual temp and the reading to keep my water at around 79 which I do I set the device to 85 anything below that and my fish is getting cold. It's nice to be able to control the temperature without being near the tank