So winter is on it's way, and I'll have to look at heating my 14 litre nano once again. During the early months, I used an in-tank heater but I want to keep as much out of the tank as possible. I could get the smallest (200w!) Hydor in-line heater but am worried that the 200w might be a bit too much wattage for the size of this tank? I'm also thinking of maybe a heating mat, either under the tank or wrapped around the filter, but that way the tank will always be x degrees C above the room temperature. In addition, when I move to the new house, we can't have the heating on too much for the walls to dry out properly. Any tips, comments, experience would be very welcome!