Perlite is a "pretty good" substitute for pumice. It is in fact quarried from rhyolite deposits, it is a form of pumice. The mined perlite is flash heated, the steam "pops like popcorn" the granules. I believe in its raw form perlite is considered a rhyolite tuft. Rhyolite, pumice, scoria, lava, all are volcanic products with overlapping chemistry. Main differences are pore sizes.
In shallow pots, perlite does "float" enough to be a problem. A thin layer of long fiber sphagnum, or a layer of living moss can nicely hold the perlite in place. In larger pots "floating" is not an issue.
Regardless of what media you choose to use, single component mixes tend to have serious problems. For example blends of perlite & Napa 8822 will be much better than 100% one or the other. Most of use use 3 component mixes, and it is important to get particle sizes in the same size range.
For example. Medium pumice and a chunky coarse grade of Turface is a nice mix. Particles the same size. Pumice and Napa 8822 is a bad mix, pumice is much too large compared to 8822. Dry Stall pumice (no longer in business) was a very fine grain pumice. Dry Stall & 8822 was an excellent mix, because the particles were the same size.
A set of sieves will vastly improve any bonsai mix you make. Get rid of fines, get rid of coarse chunks. Sieves are not that expensive and are well worth the the time it takes to sift your media.
A Soil Sifter is used to sift your soil before repotting to remove dust and to achieve a unified soil particle size.
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