The current set-up to add mass and keep dirt from dissolving is to add most of a bag of large 1", not pea pebbles, but the next step up, brown pebbles mixed all between the dirt (got at Lowe's, called Country something), and this is in a clear 33 gallon sterilite container, so I'm probably adding more dirt than most (3 to 4 inches with the rocks too mixed in), but I've reduced the amount by half. The dirt I'm using is mostly lower clay from outdoors (seems to hold together better), but I had dried it into adobe bricks then rehydrated them and put them in

I accidentally got the dried grass clippings mixed with dirt (then filled with water and placed outdoors in the sun for 2 weeks) to compost/heat and manure smell which kept the dirt from souring.

Then I add small amount of sand mixed with pool filter sand to keep dirt from escaping on top.

I plan on having a small composter, indoors, with some type of heat, like in making sake, a sake box, but a small composter to constantly add small foam on top (if I do that, I'll post the pictures), because I think an outdoor composter may be too hard to control the heat/too much composting. The idea is that the foam may draw itself out through a larger tube out the top into the aquarium by force of pressure.