I am curious if I were to add worms to the soil, would it help the biosystem, or hurt it? I have two tanks, the large is a 30 gallon, the small is a 20 Gallon. I put the soil in both tanks at the same time. top is 1 inch of white playground sand from home depot. mid layer is organic potting soil, from home depot, 1-2 inches bottom layer is organic Peat moss, 1 inch deep I host a bunch of mystery snails, and have some extra baby rabbit snails. I have plants in the tank, but so far only can get my floating anubis to grow. nothing has taken root, prolly sand is too deep. I have a top smattering of gravel to avoid plain sandscape. I have mopani, and drift woods in both tanks, they both tannin the water. the peat moss is deep, so no much tannin from that at the moment. What kind of worms would like this environment?