He is pretty small, yes, but in a 20 l Nano basin still too much technology. It would be better as an external filter with heating, but there are unfortunately only starting from 100 Watts. At the temperature indication to 28 ° - perhaps at a room temperature of 21 °? Store at room temperature of 16 ° and 20 l basin he comes up to 25-26 °. If the room temperature even at 10 ° or excluded ..? ..bekommen the fish cold feet :)
