In soil, phosphorus and calcium and magnesium are available when ph is above 6.5. If we grow at 6.4 or below we're going to suffer deficiencies of these? Then why are we never directed to grow at 6.8 where almost everything is available? Then iron and something else I can't identify are not available. Are we supposed to alter the ph to capture all nutrients and how do you do this?

I am in soil too, what I'm finding out its a combination of all thing's needed for a productive grow and good nutrient absorption with these plant's, well drained soil, their environment- "tent's" or other reflective spaces for plants, lighting, nutrients (which is a whole post by itself), and love. Wish you much success with your grows.