AsNoriuanswered grow question 3 years ago I grew for 3 years in pro mix hp
It works better if treated in lower than soil pH. I was going with 6.0-6.2.
Did magic some years ago, later I could not buy it in UK anymore, went to BioBizz and never looked back. It's a very decent product ! Never had any Cal mag issues, but I grew under HP's then.
All the Best !