... we were told NOT to use a lot of detergent since detergent or soap will develope a film that will make your tank sensors useless, ...
The GEO method specifically calls for the original Dawn..
Ok, so I've read multiple places that using Calgon powder water softener helps clean the black tank. But I can't find Calgon powder. All Walmart has is the liquid. Will that work? How about water softener pellets? Will they work like ice while they dissolve to break up the solids?
Adding water softener does NOT break up waste solids in a holding tank. Nor will it control odors. All it will do is soften your "waste water" and foul your sensors. :R
Using detergents like Dawn that are concentrated in a holding tank in a moving RV, FOAM up, which will render your gauges DOA.
Holding tank chemicals that have been used for eons in Marine and RV holding tanks are sold for a reason. Control odor, actually break down waste to eliminate any clogs that can and do happen when gravity dumping thru a 4 inch pipe. Just saying. mystical mystery treatments found on the internet for holding tanks are just that!