Review on IOAOI 50W Aquarium Heater for up to 20 Gallon Tanks - Shatterproof, Suitable for Marine and Fresh Water - Engineering Plastic Tube & Stainless Steel Inside - Adjustable Temperature by Stacy Hall

I waited a year to replace a broken old pro heater (was a great heater) because I had several different replacement 50w heaters (including a redesigned Pros) that either wouldn't turn on or failed for a few days. I bought this based on another reviewer who recommended it as a replacement for a professional heater. Very happy with my purchase. As another reviewer noted, setting the temperature is a bit tricky as you have to press down on the dial to turn it (while holding the heater with your other hand) as the gasket is tough otherwise the dial will seem to turn on like you have the heating is not actually switched on. I only had to adjust it twice to get the temperature I wanted, so it's really not a problem. The heater works great and keeps a stable temperature.