Akuaclear Combination Resin is a composite of carbon and zeollite in proportions needed to manage the higher biological load common to aquariums compared to the biological load in natural bodies of water.  The effectiveness of Akuaclear Combination Resin w/ Carbon & Zeolite depends on the amount of organic material present, aquarium load, and water conditions.  Always perform regular water tests to make accurate assessments of your tank's health.