Hello cbruni.. well you geo method has gotten such a large splash ,I just had to try it .. Here's my take . I doubt I'll ever be able to sanitize a holding tank that holds human waste ,But I sure would like to have all the contents drain at the dump station and not leave any clumps of paper or whatever behind. So I started adding the water softener (Calgon) at the middle of last season 2004, in our Jayco 5th.The immediate result of that was all the paper and other clumps dissolved and passed out of the sewer hose easily and efficiently. One extra flush with the San-T-Flush and the job is complete. If we are at a dump station where I would not go through an extra flush in order not to hold up other folks waiting ,I now have the confidence that the black holding tank does not have any extra 'stuff' left behind to cause a problem later on.
We have since traded the Jayco for a 06' BigHorn and I use the same treatment in the new 45 gal tanks.
So thanks for doing the research and providing us (the RV'ing community) with a simple and easy system using commonly available materials.
See you down the road........Frank C