Hi was thinking of getting 2 fluval 200watt E series heaters for my 240l tank,would this be overkill?was thinking that if there bigger they wont have to be on as long as the 100watt ones which are recommended for a tank size of 120l. Was going to have them both running and one acting as a back up heater just in case one failed.any advice much appreciated. Also anyone got one of these and how good are they, has quite a bit of positive feedback on the net.