Oase Hel-X 13 Biomedia - 800ml size-22g This dock is designed to

This dock is designed to adjust with the water level

when food is used regularly

Reliable: Extremely powerful and reliable in continuous use

Back filter system with included sponge and ceramic noodles

Oase Hel-X 13 Biomedia - 800ml size-22g This dock is designed toThe Hel X 13 BioMedia for the BioMaster 250, 350, or 600 includes a replacement BioMedia allotment. The allotment contains 0. 3 gallons of Hel X BioMedia. Hel X BioMedia has a large surface area across this suspending media form which is ideal for biological filtration. It is best to only replace the BioMedia when you do a complete tank restart as to not disturb the beneficial biological load.