Also just to say, it can be difficult to locate stargrass since it doesn't ship well. I got my stargrass from a friend, and my LFS buys it off local aquarists. The scientific name is Heteranthera zosterifolia. Not sure why it ships so badly, I read it is delicate, but I find it holds up well to 7 BN plecos blasting though it for food. Also I don't spend much time trimming, in my 5 foot tank, i'll spend maybe 5 mins trimming and replanting a week if that.I won't be siphoning the stuff building up at the bottom, I want to deal with it in a way that it cycles back into the system. I don't have a filter at all, and I meant amazon sword grass. I'm also trying to find a plant with minimum trimming, but I'll look into stargrass
It's the only plant I've been able to grow in pea gravel except for Hemianthus micranthemoides (baby tears), but it requires more trimming and if you don't stay on it, it will grow so thick and smother itself out, causing the lower leaves to melt and the whole carpet starts to rise and detach.
I can't help you with the incorporating the mulm back into the system because I believe in siphoning the substrate (at least a skim siphon). But stargrass would hide it lol!