I have a fluval 50 watt led heater... Love it! I can visually tell if temp in correct range by readout color..red:too hot,blue:too cool ,green:just right..you set temp u want after geater calibrates easy directions... Plus a cage to prevent damage! Aqueon pros are good too my bro uses those in his sw tanks(3 of them) i had an eheim jager,piece of junk had to be constantly recalibrated.....