Perlite is neutral compound like light rocks, wash first then add to your medium, its great to avoids nute burn in soils and avoid root compaction ..also allows considerable air into the medium, but like me the shit always floats to the top after a few watering no matter stick in back, in soil grows 30% of the pot is the best tho I've not used it in cococ, wash that too 3rd world fucks claim they have at source ,,,,yeah right or suffer unexplained nute burn issues ...?