Gary is a master with formula the key to this is the Pumice i sell high quality pumice 29 dollars per 25 pounds that includes shipping anywere in usa, pumice can be used 25 to 50 percent of mix but never below 25 percent in a pot, if mulch products used ONLY on very top layer, sand will make pots heavy and for some i wonder if a higher percent of perlite would be better,the pumice i sell has some sand size pumice mixed in i think this performs better than the screened pumice but both types are excellent, dont forget peat also can break down and degrade over time so i wonder if repotting or getting trees in ground is idea for long term, never use processed forest products down low in pot once again if used at all only on very top surface.Garys trees look far better than most nurserys but then many are still potting in a mix that will rot the roots.Avocado roots love to be able to drain and breath.