Maintenance is part of this hobby and every fish keeper wants to know how to change aquarium water easily. We'll go through the step by step process of how to do a complete aquarium cleaning while accomplishing an easy aquarium water change. In my aquarium my fish have become accustomed to an 80% weekly water change. Changing this amount of water drastically reduces the Nitrate levels in the water but can also stress your fish if not done correctly. New water parameters must be identical to the