Hello from a fellow Minnesotan. I own a 2015 Winnebago ERA 70A, bought used from a rural owner. I have always filtered any well water put into the fresh water tank or used city water, and religiously treated the black tank with liquid chemicals. The black tank is back flushed when emptied, sometimes flushed by a wand from the toilet side. There is never any #2 or paper put into the black tank, just urine. To prolong days between dumps, after reading a thread here, we have been using a spray bottle to "flush" the bowl after dumping the urine into the black tank without engaging the water pump. There is some kind of scale or mineral deposit flushing out of the black tank. Can a product like CLR, LimeAway, or even vinegar be safely used to treat/remove deposits from the tank? Your input is greatly appreciated!!