Yes, there is a mixture of stones. Some days I guess that their sizing sieve is broken or has holes in it allowing the sizes to mix.
But regardless, if I am using aliflor straight, different sizes do not really matter. I order medium and I might find 5% coarse and 5% small within the bag. That is not a problem really.
If it is in a mix like mine, size really doesn't make a difference either.
I was just thinking about this yesterday. About 10-12 years ago, Krull/Smith was selling all of its' large Cattleyas in a media called "Stalite". That looks like medium gray Grow Stones. They swore by it as a media. My first though was, "This stuff is extremely heavy!!!" It might have been wonderful for keeping plants upright, hard to knock over but I thought about the stress added by 20 or 30 plants like that on a bench top!
Look carefully at my mix above. You can easily see different sizes of aliflor. But I carefully select my media within my media if that makes any sense???? If I am potting a big Cattleya, I gather up handfuls favoring aliflor, charcoal, perlite and medium bark.
If I am potting up a Paph., or an Oncidium, something requiring more moisture, my selected handfuls become more about seedling bark, perlite and charcoal. I kind of stay away from a lot of aliflor and medium bark on purpose.
