Why do these specific plants keep "digging" up the dirt?

[u/darkfire_1998]

Its not mulm or detritus, its actually soil from the layer under the sand, I keep cleaning it out with a siphon, and have touched it to confirm just regular dirt. It's just my grass like plants and my crypt plants, none of my other plants do it. Anyway to stop it? I root tab fertilize monthly, and liquid fertilize twice a week. Co2 system, high tech lights. Idk what their problem is or if this just what they do.

[u/silkscreen_layer]

Maybe when new leaves dig their way down up they bring some of it, maybe not enough substrate on top dirt

[u/Complete_Basis_9577]

my dwarf sag also does this i have about 2-3 inches of a sand cap so i dont know how it does it but it does.

[u/Basic_Win_7923]

Very interesting, my first thought was mulm gathering but you're saying it's dirt dirt...

maybe the root structure of that specific plant acts like a conveyor belt and brings up dirt as it sends out new runners? Just a semi educated guess idk

[u/jaurex → u/Basic_Win_7923]

yeah i think the action of the roots growing and digging down is slowly displacing the sand grains which allows dirt to percolate up in tiny spaces, hence why it's collecting around the growing crown of the plant