Just a note on several questions that were raised in prior posts. Most of the pumice we have here in the US (not included the bags shipped from Japan) are domestically sourced. As a volcanic rock, there are large deposits of pumice found in California, Oregon, Idaho, New Mexico, and Kansas that produce most of the pumice we have here. Unless there are chemical analyses of Japanese pumice that show it contains minerals not found in US pumice, I'd say stick with domestic pumice produced by US workers!
Regarding the question of Akadama vs Turface vs Oil Dry/kitty litter, there are some definite differences between what each provides to the soil mix. Akadama is a type of Japanese soil. Keep in mind that the islands of Japan have a volcanic origin, so their soils have unique mineral characteristics based upon the types of volcanic rocks that were eroded and created their soils. The same can be said of soils anywhere, they're the result of the erosion of continental and oceanic rocks over geologic time. Wherever the product is mined, the aggregate will generally have chemical and mineralogical differences, some of which may be more beneficial to the plants we grow. Just an FYI, today I did a search of eBay and Etsy and found a numbers of sites that offered what I consider good deals on Akadama as well as soil mixes that contain Akadama. Several of the sellers offered free shipping, so it becomes a bit easier to justify Akadama over other products shen you're not paying a separate shipping charge. And keep in mind, Akadama does slowly disintegrate over time, but the resulting material is still a beneficial part of the potting soil that plants are able to use.
Finally, having had cats for years and having purchased different types of clay kitty litter, you may want to consider starting with a small bag, taking a sample, and adding water to it. I've seen some where the litter has quickly broken down to a sticky clay when water was introduced (generally the cheaper brands). And avoid scoopable litters. There is a reason that they are so easy to scoop, as they clump together in the presence of moisture. A couple of years ago I dumped a pan at the tree line several hundred feet from the house. Six months later I went back and it was like a lump of concrete. So far, the best of the clay litters I've seen is Oil Dry, which does seem to retain its structure over a longer period of time.
. I have used some coarse lava in bottom of a couple of pots just for this and adds drainage as well. Organics do break down and settle in pot as well as clogging drainage. If growing deciduous or trees needing repotted 2 years or less organics can be good but for most conifers, older trees and Yamadori not re potted for several years inorganic is probably better choice.
