Originally Posted by Ustamiata
I've read the thread started by Boeing Guy -- but here's a similar question: After 4+ years of full timing, I'm pretty sure there is a build up of gunk (food, hair, etc.) in the bottom of the gray water holding tank that does not drain out, and smells. The additive we use in the black water holding tank does not seem to affect it. Question: What products have you all used to clean the gunk out of the gray water holing tank that will not hurt the plumbing or the tank?
Ace hardware sells a product that I use on my house drains (I live with three women, my wife and two daughters, who constantly plug up the shower and sink drains). It melts greese and hair on contact. I suspect that it is just a strong hydrolcholric acid (it doesnt say what the active ingredient is).
I am sorry that i cant remember the name, but it comes in white bottles, wrapped in a clear plastic bag. The labeling suggests industrial use, as it is not a very fancy package. At my local Ace, it lives next to the Draino.
I have little doubt that this would liquify any solids left in either waste tank. It does react to water, wich causes it to boil and give off strong gasses for a short period, so keep your head away from the drain as you pour.
After it dwells in the tank for a little while, you probably will want to rinse, or at least dilute with clear water by filling the tank, and then draining.
To make sure you have adequatly covered the dry stuff, you may need to put a gallon or so into the tank I think.
For this very reason, I decided to stop leaving my tank drains open when camping with hook-ups. I think that the waste needs to float away, and it there isn't water in the tank, it really can't float. If you are in a hot and dry climate, then the waste will likely solidify, causing build up. I choose to simply wait until the tank is full, then open the drains and empty the tanks. Then I close the tank drains, and add several gallons of water to the waste tank to prime it for use.