We spent a while finding a good sand for our uses. We finally found this and it is great stuff! Its large grain-size results prevents it from compacting densely. Silica sand is chemically inert and does not release minerals.
We use this in several of our mixes:
Sarracenia, Drosera, and VFTs: 1 part sand, 1 part peat
Cephalotus: 2 parts sand, 1 part peat
We also use this sand as a top cover for pots of Cephalotus in order to prevent nuisance moss from taking over.