i just got an emperor 280. so im gonna use it in my 30 gallon, and get ride of the top fin 30 thats in there. im useing the rite-size e cartridge that it calls for, what should i use in the refillable media container if anything ? the tank has a few live plants and drift wood that still seems to be giveing off a little tannins. the fish are a convict pair 3 and 4 in. and a 5 in. jack dempsey. thanx sean