Liquid fabric softener and black/gray tank smell

Before we leave for the CG, I add 1/2 cup Calgon water softener,(powder), a good squirt of dish detergent, in about 4 gallons of water-divide into the black and grey tanks. At the dump station, dump black first, then grey. Close valves-add another bucket of soapy water to black tank, open valves. A couple more buckets of water into black tank. Close valves. Add another bucket of water, Calgon, bleach tabs, dish soap for the ride home. When we get home, rinse grey and black tanks until clear.I have a hose tip that I can put down into the toilet. Close valves, keep some soapy water in the tank-don't let the tanks dry. I also clean the sewer hose in bleach/soapy water. This can only be done if you have access to a good sewer.