Oase BioMaster 2The most convenient filter on the market! The Easy Clean pre filter module simplifies routine cleaning & extends the life of the main filter foams. Combined with the no mess maintenance features, the BioMaster 2 minimizes the time & effort required to keep your aquarium pristine. Superior water clarity Experience crystal clear water thanks to the optimized flow, sealed 4 stage filtration pathways (pre filter, two foam levels, & biomedia), &