Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Turface is very light and will end up on top, no matter where you put it.
I would redo the whole tank, get rid of the sand and gravel and just go with Turface, if that is the substrate you want. Anytime I mixed or layered Turface with any size sand or gravel, it never looked right.
Sand sank through it, no matter how well mixed to begin with.
Pebbles drifted around through it, gradually sinking.
Pool filter sand is OK, but I would not go to any effort to add or swap what you have for PFS. If you are going to do something, use your energy to make it better, not swap the same materials around.
Basically only a few types:
High CEC (fine particles like baked clays, certain very fine organic matter. Turface)
No CEC (Sand, gravel, coarser organic matter)