Blackwood wrote: My mix mainly using this fired clay, sand, compost, and ordinary potting soil depends on tree.

You are loosing the benefits of the coars granules you are putting in your mixture, by adding potting soil and sand/compost. The idea of modern substrate is that is allows for loads of gas exchange, and easy drainage: Full control over the root growing condition.
I hear what you say about drying out; Consider adding coarse organics instead.