First of all, when do you dump the black tank? Maybe I missed it, but I did not see where you were dumping the black tank! NEVER, leave the valves open on RV holding tanks. If it were me I would dump them after every weekend, no need leaving all the "stuff" in there until the tank is full. The comments on adding at least 5 gallons of water after dumping is spot on, these things are designed to have water in them, don't skimp! Also, no bleach, is because the bleach will kill all the bacteria! Bacteria feed on the "stuff" and break it down so it can be washed away. It does that in the holding tank as well as the septic systems. Rid-X promotes the growth of the bacteria. I think they call it "the circle of life", or something like that!