Diatomite
50lt bag

Diatomite is 'diatomaceous earth'. It is mined in Qld and contains the highest form of plant available silica of any medium on the market.
The two main benefits of using diatomite as a growing medium are its irregular shape and its water holding capacity.
It is great as a medium on its own or mixed with coco peat, rockwool or perlite.
It makes a great seedling and orchid mix when combined with coco peat and a little perlite.
Diatomite can be used in any hydroponic system.