well Piotr, you have to bare in mind that there is a big difference in the two species. The Geo's do much more sifting the sand then the Guianacara's. It really it very different.
I had the both species in my tank, G.Pindare and these guys. I try'd it first with leaves, but in a day al the leaves where under the sand.
The Guianacara's are sometime's sifting the sand to but not in the extant of the Geo's. The pick up things and look under and above pieces of wood to see if there's anything to eat.
When I had only the G.Pindare in my tank I used bigger peaces of wood and branches on the bottom. And every week I had to find them and place them back on the sand.