EFFECTIVE WATER FILTRATION: Effectively filter water in koi and fish ponds, water gardens and aquaculture systems. COMPATIBLE: Works in virtually any waterfall tank or biofilter! MESH MEDIA BAG: Includes red mesh bag(s) for the koi cubes Note: Bag and cube color may vary. FEATURES LARGE SURFACE AREA: Each cubic foot of cubes has approx. 525 sq. ft. of surface area to support beneficial bacteria colonization. INCLUDES BENEFICIAL BACTERIA: Includes Green Vista Hydro-Bugs Beneficial Bacteria for biological filters. Green Vista's Rainbow Koi Kubes provide high surface coverage and effective filtration in ponds, water gardens or aquaculture systems. They are a great upgrade for any brand of waterfall or biofilter tank and last 2 to 3 years plus! The universal cubes are various densities, shapes and colors of fish safe aquatic filter media and range from 1 to 3 inches. Save the time and effort of cutting filter mat to the specific size of your waterfall tank or biofilter by using these cubes! They are custom cut from sheets of foam filter material. Clean the bio cubes as needed by simply rinsing a bag of them with water from a garden hose. Superior Substrate for Beneficial Bacteria Colonization: These biological cubes cover roughly 525 square feet of surface area per cubic foot, much more than lava rocks, bio balls or ribbon material. The bio cubes allow your pond filter to maintain greater levels of beneficial bacteria, resulting in clearer water, improving your pond's ability to handle a larger fish load. The included Hydro-Bugs Bacteria for the biofilter will give your water feature a healthy jump start. The beneficial bacteria work with the biological cubes to filter and clean water, improving the entire pond ecosystem! Each 0.9 or cubic foot of bio cubes includes a mesh bag ($6.99 value) making the cubes easy for you to rinse, carry, and store. Please Note: The Rainbow Koi Kubes are a blend of various colors, shapes, sizes, and densities. Click "Add to Cart" Today!