Since I am having a difficult time sourcing pumice in the Heart of Dixie, I have been looking at alternatives. I read about Optisorb on my favorite bonsai forum, www.bonsainut.com , and found out that it was available a Oriley's for $16.99 for a 25 pound bag. I checked with my local store and they had it, so I bought a bag.
Before we start sifting, let's talk a little about diamataceous earth. Breathing the dust is very bad for you, it can cause a condition called silicosis. So, before you start sifting, purchase yourself a quality dust mask. Not the cheapos from Walmart, but get the ones from 3M, they aren't too pricy and offer much more protection. You can get them at Home Dept, Lowe's, or most painting stores.
Upon opening the bag, here is what you will see, That is a penny in the picture, I found it in a parking lot so it is a little worn.
I did some sifting and out of 25 pounds I got about six gallons of material that was between 1/4 inch and 1/8 inch, just right for my mix. The fines are a uniform size also and should make a good substrate for mame and cuttings. I don't know if this will be as good as pumice, but it looks like a good replacement until I can locate a soure. I will report back my findings.
