Ok...so it is making since to leave valve closed for a few days, and showers, then open it and let it drain. Probably leaving it open will allow the bottom to dry out alot, and leave residue to build up, like shower and sink soap scum.
I use 'dial' bar soap once a day. To help keep the tank clean, and the garden hose from clogging, I have a strainer in the shower drain, and clean it out after each shower.
I never knew I 'shed' so much hair.
Can't get ICE down into the grey tank. There is a built-in spray cleaner on the black tank, that I use every time I drain it.
I am liking the bleach idea. I can ad some in all the drains before I drive away after sitting here for a few months. That way it will clean/sanitize the drains, traps, and pipes on its way to the grey tank. It will then 'slosh; around in the tank until I dump at the campground/rv park.
But will bleach (clorine) actually clean/disolve scum ????