Last year, I found that adding just 10% coconut husk chunks by volume vastly improved the vigor of the plants I had potted in 8822. I would consider a of 9 to 1 mix of 8822 and coconut husk chunks to be a decent budget-conscious bonsai substrate for moisture-loving trees in shallow pots. For high-end trees, I would just spend the money on Akadama and pumice. Roots would grow through, as well as between the chunks of coconut husk, and that made it a bit more difficult to sort out the roots when repotting.
For deeper pots for trees in development, my ratio was closer to 60/40 by volume. The 8822 is a water-retentive particle that prevents the coconut husk from compacting into a brick in a container, but the higher proportion of husk chunks provided better fertilizer absorption for faster growth. Higher proportions of coconut husk were far too wet and tended to compact into a brick, which stunted the trees growing in it.
This year, I'm shifting to good old reliable perlite with about 10% vermiculite mixed in for water retention, and a layer of 8822 on the surface to weigh it down, plus a bit of sphagnum moss to encourage moss to grow on the surface of my pots.
Pretty much all of my material is developing in oversized containers, and perlite is both lighter and easier to buy in bulk, so it's great for larger pots and growing bags. The big drawback is that it's lighter than water, and it can blow away in the wind. A top dressing of 8822 easily remedies both problems.
