Why perlite?

Hi, I checked a lot of questions and didn’t find an answer. I was wondering why would you use perlite when it contains asbestos and can be harmful if inhaled. Why not use sand or something else natural like sea sponge bits. Also is it possible to make your own nutrient solution from scratch? If so, what recipe? To me it seems that the continuous flow technique would be the most simple, but I understand the use for a medium for root vegetables. Thanks. -Tony

Hello Tony

Good questions
No asbestos – that’s a different mineral to Perlite – whoever told you that Perlite is anything but perlite is dreaming.
(safety sheet http://www.schundler.com/msdsperl.htm is an example of what tests done on Perlite result in)
Perlite is a rock mined from the ground, heated to sterilise it and make it pop’ and allow the particle to hold water inside the structure of the particle. No safety issues other than nuscience dust – could make you cough. No harm if swallowed, no harm if in contact with it. Its sterilised dirt or rock – not synthetic.
Safe, natural and non-harmful.
Why not sand. Well, expanded mediums hold their water away from roots (inside the perlite particle) releasing moisture to the roots in contact with moist particles. This means providing more air space between the particles, better drainage, better moisture holding without rotting roots, and higher growth rates than non-expanded mediums.
I have included another reply for you below to read with the perlite safety references. Natural media can be used, not necessarily safe, not sterile (disease/bacteria), may hold water between particles, not inside the particles, leading to pooling and rotting roots, may break down and release other nutrients rendering nutrient solutions difficult to manage.
Making your own solution is simple. You will not find that a simple solution gives much performance. When adding components, the solution in concentrate will get hot, or very cold, and the order you add them will affect the solubility/availability. I don’t have a recipe, but you might find one in a book. It may be expensive to buy the components, some packs would last a grower 1000 years, and is quite expensive.
Continuous flow I assume you mean channels, as this is the only way I feel you can run nutrient continuously. Channels can absorb heat. If the nutrients get above 30 degrees problems will develop as oxygen can no longer be absorbed. On a scale of easy to difficult, NFT channels are closest to difficult, and a media system is the easiest. For system information go to www.hydrocentre.com.au/catalogue