agreed to postalpenguin about the failures. i bought a 400w marineland for my 120 about 4 months ago. the piece of junk could never keep the water close to where i had the temp set. so, i set up a 75 (which this sits beside an airconditoner) again, couldnt keep 75g of water close. I ended up using 2 hydor 400w heaters, one in each tank. I actually got these at a yardsale (with a 55g, hoods, lights, plants, chemicals, penguin 200, some whisper filter and a rena xp4. all were in mint condition and i only paid $25 for it all!) but they work awesome. couldnt as for a more consistant heater.