Ive been using promix xp for 7 years and while i have used it out of the bag it has a low ph. Ive found a tbs of extra dolomite per dry gallon of promix and flushing.in 8.0 water gave me 6.3-6.5. Whoop Whoop fam, mcl
Unfortunately, pro-mix hp is very lacking as far as a soil component. You will see much better results mixing it evenly with a diversity of other ingredients such as forest litter compost or chicken manure, perhaps a boxed pelletized organic fertilizer and some minerals such as clay (about 5 cups per cf or %2-5) and pumice, as well as 5 percent sand. The more difersity of microbes the better, you cna even purchase a soil inoculant online or grow the bacteria your self in the forest.
It all depends on how a person grows. I do not like to let my plants auto feed. I prefer the plant to feed what i give it and when i choose to feed it. If i have to flush for some reason the organics materials wont flush out. Promix works just fine. Its a matter of personal preference.