Drewski answered that question a bit ago- I dont know how to link threads.
" Just a note on N2. An N2 cartridge is ONLY good for 1 tub of water. If you lose (remove then add) more than 1/3 of tub volume, N2 is no longer effective and you are wasting $. This is because the ionization process N2 uses is completed in the first 36 HRS after adding it to the water and the chemical change to the contents of the cartridge means it no longer has the capacity to treat "new" water. Keep this in mind if you go through water. "
the thread was "Cloudy water"
