Several months ago I plumbed in a nitrate filter cartridge into the water line I use for python water exchange. I did this because my well water runs a nitrate level of about 25 ppm. The filter brought the nitrate concentration to undetectable but unfortunately the cartridge capacity was not great. Once I filtered about 90 gallons of well water the nitrate concentration started to rise. It is too costly to buy a nitrate filter cartridge every quarter. I am back to using API Nitro Absorb pillow. I keep the resin bag in the filter for 24 hours after water exchange and this brings my tank nitrate concentration down to around 5 ppm.
