You will need to buy something to attatch the Juwel heater to the tank. When I took my Juwel filter out, I used part of a Visitherm (I think) heater cover. They sell them in Pets At Home, among other places, and they come in sections. One has suckers on it to attatch it to the tank. You can also buy other sections which clip onto the sucker one to make a sleeve to cover the whole heater. I don't use whole covers in my community and livebearer tanks, just the bit with the suckers on. I do use a whole cover in the betta's tank though as he likes to sleep wedged vertically between the heater and the filter.