All the 3 systems are interchangeable and use a different type of cleaning agent. The 8100 and 8200 use a soft soap or surfactant to help clean the bowl and the 8300 uses our “organic” bleach to help keep the toilet bowl white and clean.  The 8100 and 8200 are the preferred cleaners to use with a septic system, the 8200 comes with added cultures to help maintain your septic system and the 8300 is a bleach product and should not be used with any septic system