AusBonsai

I've noticed a bit of posting about a reduction in diatomite quality the last year or so. I've never used it but I don't want to risk my trees with it. Now that I've moved I'm not finding scoria that easy to find in the 5mm size. Are there other inorganic materials other than sand that I can use in my potting mix that I can easily get in Adelaide? How is pumice different from diatomite and scoria? Are there other options?

You can try Growstone. It's like a man made pumice. Your local Hydroponic shop will have it. I tried it on my white pines this spring and they are all doing well in it. I used it at about 60/40 with bark and a bit of my clay pellets.
It's quite alkaline at first so I would recommend washing it a couple of times to remove some of the fine CalCarbonate before use. There are 2 sizes available.

Nope they are different.
I am using both now in my mix with Zeolite as well.

Check out the wiki for some basic info and links to other sites

https://www.ausbonsai.com.au/wiki/index. ... =Diatomite

Ken

Personally stopped using diatomite completely due to quality. Switched to pumice, if I cannot get pumice then scoria which I have no issues using either. Add this to bark as main components and small amounts zeolite, perlite and coit.

Big difference is pumice / scoria retains its structure doesn't colapse and turn to mush in the pot.

Think it comes to supplier, some people are happy with diatomite, personally cannot see me using it again at this stage.