Filter generating too much heat?

Am I supposed to do something special when I get a new heater? I didn't know that.

So the visitherm has a thermostat with fixed temperature, so it doesn't work off a differential of the ambient temperature. But I have unplugged it and the temp is seems to be going down a bit.

This is a little 5g tank with a 25w heater.
 
Ok just so you know the temp settings that they put on the termostat is not accurate. It is a guide, I have one that I have to set a few degrees below what I want and it stays there. Click yours down a couple of degrees and plug it back in, you will need to find what setting will give you your desired temp. And with all thermostats they should be put in the water for a few minutes (they always say 15) before you plug them in. It is the same when you remove them from a tank you unplug them and let them sit for a few minutes. It is to minimize breakage.
 
Jericho said:
Ok just so you know the temp settings that they put on the termostat is not accurate. It is a guide, I have one that I have to set a few degrees below what I want and it stays there. Click yours down a couple of degrees and plug it back in, you will need to find what setting will give you your desired temp.

Yeah it turns out the heater's temp dial is off by a few degrees. I turned it down to about 79 and the tank has been rock solid at 80-82 depending on which thermometer I am looking at.
 
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