BIO-Cubes are made from 100% biologically degradable polymers that effectively remove both nitrates and phosphates from both marine and freshwater systems. BIO-Cubes have a very high surface area and contain 400% more carbohydrates than any other brand, making it the best product of its kind in the world. Independent testing in real world scenarios has proven BIO-Cubes to far outperform all other competing products. No other product of its kind can compare with the explosive performance that BIO-Cubes can offer. BIO-Cubes are very versatile and can be used in filter bags, fluidized reactors and denitrators. BIO-Cubes require no maintenance and require no feeding dosages making it the easiest and most convenient nitrate and phosphate removing product on the market. Nitra-Guard BIO-Cubes comes with a free filter bag with every jar.