Bests & Worsts Reviews from Amazon

Great heater and very precise. Its within .5 degrees of my thermometers. There are a few steps one must follow in order to get it working correctly. I wish Fluval would update their manual, as setting up this heater vertically per their instructions is wrong. Their support will tell you updated instructions on how to set it up correctly if you contact them... Here is what I did so it worked flawlessly: 1- It HAS to be mounted in a 45 degree angle, and with the bottom end pointing towards your filter intake. If you can also point your filter's output to push water towards it, even better. Look at my picture and you will see how I have it, and absolutely NO "Low flow" messages at all. 2- Let it rest in your aquarium for about 20 mins, then plug it in and wait around a minute before setting any temps (it does a self test and goes thru some heating on and off to calibrate itself). 3- Don't expect it to heat your aquarium right away. Its a very gentle heater. It took it around 2 days to finally take my 65 gallon tank to the desired temp (it wasn't that bad, as I had filled it up with water within 2 o 3 degrees off from the desired temp, which is what Fluval recommends in their manual), so make sure your water is close to the temp you want. Once it reaches the desired temp, it turns green and the temperature stays there, no variances unlike other heaters (granted you followed N#1). 4- I know its a lot of things to do compared to "dumb" heaters, but trust me, once you get it working ok, its the best, most accurate heater I've had (I've had eheims, marinelands, etc). Since its a smart and very VISUAL heater, it will tell you everything is going on, so don't be surprised if it stays blue or red for a long time, little changes in temps, and it will let you know. Don't let this worry you, we are used to "dumb" heaters that only have a on/off light, you think they're working, but they are not telling you if your water is down 2 degrees off, or other things like this one. Hope the above helps, and again, took one star down, only because its Fluval's fault for not printing a better manual, that explains the points above, and waiting for customers to contact them/complain to finally send an email explaining those things.