Aquael Ultra heater keeps changing my set temperature

[swiss1939]

I have been using a brand new Aquael 100w Ultra heater and I swear this thing keeps changing the set temperature. I have it set to 78 degrees, and it seems when the temp goes up during the day with lights on and when I am out (AC automatically turns up a little), after a while where the heater is reading water temp is at 80 while my heater is set to 78 degrees, it will just switch to being set at 80 degrees. LIke what the heck?! I didn't set this to 80. I can't figure out if this is some strange setting on this heater or what's going on.

Anyone else have issues with these heaters?

 

[Rocks reef]

Since it is manual control. There isn't a way for the heater to reset to a new temperature. If you say your temp goes up when the lights are on, that is the issue. It takes a while for the water to cool down. Say if the water is 80 degrees and you are waiting for it to cool down to 78... .it's gonna take a hot minute. Especially if the temp in your house is close to 78 degrees.