^ the chloramine filters using cartridges that you refill with carbon. the activated carbon goes for about $30 for a 5lb bag and each fill last several thousand gallons. they also sell carbon block filters which are a little better and last up to 20k gallons. these are about $16 each
im really hoping this water changer gets my nitrates down. as even after doing a huge weekly water change my nitrates are still in the 80ppm range 