Review on 500W LANZZ Submersible Aquarium Heater with Auto Thermostat, Protective Sleeve, and 3 Suckers - Optimize your Fish Tank Heating System by Andrea Bone

The heater failed in just under 30 days. Revain replaced the heater and the replacement failed within 30 days. As I researched different brands of heaters, I learned that low water flow can cause high wattage heaters to fail. My Lanzz heater was built into the tub of my aquarium. Water flow is usually slowest in the swamp. The Lanzz heater can work normally when installed directly in the aquarium. You can try the H7 series heater. Not sure what brand or type these are but I use an H7 heater in two small tanks and I really like them. The only problem is that these heaters only reach 300 watts.