Our first usage issue that we ran into with the new RV was with the sensors on our grey tank. We were following the recommended method for dumping our tanks where we would let the black tank fill to 66% and then use the grey tank to help flush the hose when dumping. We would end up with the grey tank filling up much quicker than the black tank, so would be dumping the grey every couple of days as it got full. After a few weeks of staying in the same park, our grey tank showed 33% full even after dumping, then after a few more weeks the tank showed 66% full even when empty.
I went to the internet to see if this was a unique issue or common problem. It turns out this is a very common problem for the RV community. The sensors are just bolts inside the tank and they get gummed up by anything that goes down the drain in either the shower, sinks or dishwasher. I tried adding in all sorts of cleaning products to the grey tank to clean it out, but nothing worked.
The common fix recommended on the web was the GEO method, Get Everything Out. I added a cup of Dawn dishwasher soap and a cup of Borax to the grey tank filled to about half as we packed up to move from Phoenix to El Paso. The drive adds the washing action to the tank and cleared everything up. If you end up getting your sensors giving full readings when the tanks are empty, try this method.
We've also decided to just leave the grey tank valve open and only close it when the black tank reaches 66% to we gather some grey water after a day to help flush the hose when dumping the black. This cut down on the number of times we were dumping and still does a decent job keeping the hose clean.
RV on!
