The tetra internal aquarium easy crystal 300filter with heating compartment for crystal clear healthy water and easy maintenancer the easycrystal filterbox is a compact space saving complete set for optimum filtration of the aquarium water mechanical and carbon filtration for crystal clear waterr one touch cartridge replacement system for easy maintenancer chamber for concealing aquarium heaterr easycrystalreg filters are extremely easy to clean replace the filter cartridge every 4 weeks