On construction type sand/ Sakrete. In my tanks with this sand all the very fine grains will settle in a thin layer between the MTS and the larger grains ofd sand.
I don't use any facing sand in my tanks so you can see the layers. Even people that keep non-planted tanks are amazed and interested when they see it.
I feel with a 1" sand Cap over 2" of MTS there is no compaction issues. MTS snails travel at least to the top of the MTS layer. This can actually be seen. I've also syphoned off a Black Diamond Cap and observed MTS emails in the Dirt below the Cap.
I believe that the thin layer of fine sand between the dirt and the rest of the larger grain sand cap material when I use Const. sand may be part of the reason I am able to use higher levels of Organic material in my Dirt mix and not see all the problems that are expected.