De*nitrate™ removes nitrates, nitrites, ammonia, and organics from both fresh and marine water. The high porosity of de*nitrate™ supports the proliferation of both aerobic and anaerobic bacteria that further remove these toxic aquarium byproducts. Even when exhausted as an organic adsorbent, de*nitrate™ continues to be an excellent support for the biological filter and does not have to be removed. This product is sold by volume. Cited weight is minimal weight.