I use a lot of pumice straight, or pumice mixed with chicken grit. I have greatly reduced my use of Turface because I find it holds too much water and too unevenly. Granted, I have to water more often with a pumice-based mix over a soil mix, but I think my plants do better in it. Can't comment on akadama, but lots of people here do have experience with it. I am sure they will chime in and share it.

You can use straight pumice or volcanic rocks and/or a combination to whatever is best available. Akadama can be used or mixed in to increase water retention.

Pine bark was just meant to be cheap filler (in many places around the world it is not cheap nor readily available). Akadama has some similarities to Turface and comes in a wider range of sizes but lower durability.

Overall, particle size is very important and getting that balance takes some practice.

Far East Floral Garden online shop sells Pine/Fir bark under the brand Orchiata

The idea of Gritty Mix is to have good drainage (3-7mm particles) while controlling retained water by adjusting the ratio of non porous substrate (granite) and porous substrate (turface mvp, leca, pumice). A 100% porous mix of Akadama and Pumice and volcanic rock might be too water retentive. But do try it out and see you need any non porous substrates mixed in.

i've been using the mixture, akadama, pumice and zoelite so far with terracotta pots and my plants seem to doing well. thanks for the heads up on the pine bark fines!! will give it a go!