Is anyone aware of research or testing of commercially available lightweight aggregates as a component of bonsai mix?
Lafarge offers Litex - described as “a sterile, inorganic medium that provides a reservoir for water. Litex can also be used as a ground cover or in soil-less mixes. Loose bulk densities range from 880-1200 Kg/m3. Product sizes range from ½-inch coarse to sands.”
Peter Chan seems very satisfied with the fine feeder roots produced by a UK product called Lytag shown in a 26 Jan 2020 YouTube video (Repotting a Privet Bonsai).