Barbara wrote: > >I have been reading with much interest the different bark mixes used >for paphs and phrags in the new Tropical Slipper Orchids book by >Koopowitz. The mixes seem to use many different materials to keep >the bark mix open, such as lava rock, perlite, charcoal and aliflor. >It got me wondering what the difference is between spongerock and >perlite. What are the different characteristics of aliflor, lava >rock, diatomite to make one more desireable in a mix than the other? >
Hello Barbara, I don't know of any chemical or structural differences between perlite and sponge rock, I've always been lead to believe the pellet size is the difference. Perlite is the tiny pellets that will swirl in a windstorm and the spongerock is usually much larger. The only differences I can really comment on for aliflor, lava rock and diatomite are the general sizes for each. Usually aliflor or clay pellets are reasonably near the same size though there can be a few tiny pieces here and there. Lava rock from what I've seen when you open a bag most of them are pretty much (from what I've seen) smaller particles than aliflor but are fairly regular in size. Diatomite can be very variable in size; the small is pretty small and usually all are small, but if you get 'large' you often get many sizes mixed together. If you wanted even 'pellets' of any of them, a screen to even out size would be helpful. I don't think either aliflor or lava rock degrades very much though I have read on a tree fern list to use it for 'nutrients' in a mix. hope this helps a little, charles -- charles ufford oriskany, ny usa _______________________________________________ the OrchidGuide Digest (OGD) [email protected] http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
