And then when you need to redo the carpet how your going to keep the cap neatly on top from the soil.
I use a thin layer of regular sand from lowe's at the very top over gravel, so you can still see just a few streaks of soil. If you pull everything out, you would scatter a thin layer of regular outdoor fine sand from lowe's, their cheap outdoor kind, again, as the sand blocks the black water from seeping up into the water. Also, using larger 2" ponds rocks from lowe's you can scatter it very lightly on top of everything and seems to help.
Also, adding sand into the original soil (and having clay in it too, from digging down below the topsoil) keeps the soil fresher, and the clay holds the soil together, combined with adding pond gravel, 1/2" brown gravel from lowe's into and mixed in with the soil to add rigidity, and you can compress it down with your hand so it's solid. I assume the compost foam from an outdoor composter that gets direct sunlight, which is just a 33 gallon clear sterilite container covered with a tarp. At the bottom of the clear container, I'm going to put soil then cover it with pea gravel and a thin layer of sand. Then a large outdoor black bag of dried grass clippings and a bag of red mulch from lowe's that smells like compost. When it generates foam on top, adding it to the water in small amounts will kill bacteria. But the difference of that composter from a regular composter (regular farm composter that is) is that the container is filled up to the top to the brim with water, whereas a farm composter is lightly added with sprinkles of water, you're trying to scoop out a cup of foam to be transferred indoors in that cup of foam to the indoor aquarium, the foam that looks like the foam at the bottom of dam that the dam stirs up, but this just bubbles up naturally and sits on top. And in the aquarium on top of that soil mixed with gravel, I cap it with pea gravel to a heights from the side total of 3 1/2 inches and then just a very thin layer of sand so the total height of everything is 3 1/2 inches. So when you mix gravel like that in with the soil initially, it's probably going to be higher from the side then than an inch, so I didn't cover it with massive amounts of pea gravel over that. The soil plus gravel mixed in was probably almost 3 inches in some places and then pea gravel over that.
I did make an outdoor container about a foot and a half cut from a plastic 6.5 gallon beer brewer, that I did cover the soil a lot higher with pea gravel, and a sword plant, but that container is outside during the day, so the sun can kill most of any bacteria at the higher gravel height vs. indoors that height wouldn't work, but the indoor larger aquarium one has a height advantage of a taller water column, so it's true in an indoor container at the very bottom the water is dirtier, but you the thin layer of sand keeps it from being black water there, and you only notice it when scooping out all the water for a water change, but it should just be lightly tan near the very bottom. I really ought to add short bulletins because this is longer to read. The sword plant in that container, the leaves sitting out of the water is from: https://aquariumplants.com/collectio...nodorus-ozelot
, and when I had it in a gallon container in the window with just sand and gravel at the bottom, and dropped in some topsoil, when I added triple ten fertilizer to that, it flowered in the window, but now it's in the larger outdoor pot outside and brought indoors at night.