I'm going to be getting a new couple of heaters for my tanks. The ones that I bought just aren't bringing the temperature up properly. They keep dropping below 75 degrees and regularly going to almost 70. (and these things are supposed to handle up to a 10 gallon tank). The heaters seem to be turning on, but they're only keeping the tank room temperature for some reason and my tanks are the bare minimum size listed for these things. It's puzzling, unless they're both defective out of the box. It says in the instructions that it will take about 24 hours for the tank to reach it's final temperature. It claims that it's supposed to keep the tank at a stable 78 degrees and it's clearly not doing that.
Now, about aquarium heater design. If I just put a new heater in, are these things designed to raise the temperature gradually as to not shock the fish with the temperature change? Is it safe to just put the heater in there and let it do it's thing or should I remove the fish for it's acclimation period?
The last thing I want to do is chill, cook, or put my fish into temperature shock.