All-natural removal of sludge, fish waste, and other unwanted organic pollutants. For all freshwater aquariums. Effectively cleans gravel substrate, filtration system, lift tubes and hoses, ornaments, plastic plants, protein skimmers and other aquarium accessories. Liquid Gravel Vac utilizes the natural sciences of aquatic environmental chemistry to formulate this powerful, one-of-a-kind product. One of the key components is billions of Mother Natures own "housekeepers": Aerobic Heterotrophic Bacteria. These little overachievers provide all-natural, stree-free removal of detrimental aquarium pollutants such as uneaten fish food and fish waste through healthy bioremediation. Helps prevent accidental suffocation of your biological filter by eliminating oxygen consuming, dead and dying organic matter