Resins can be used to change particular water parameters in an aquarium. This example of how to reduce aquarium nitrates the output of the filter is passed through some nitrate removal resin. Having the resin in an additional filter booster canister makes switching the resins for recharging simple and quick and removes the need to disturb filters too often. Also with the full flow forced to pass through all of the resin the effect is far more efficient and nitrates are significantly reduced very quickly.