I've merged two of your threads asking about magnesium as I think they are essentially asking about the same thing.
Something to understand about magnesium is that it's not in particularly high demand. Depending on your literature source, magnesium makes a bit less of a contribution to the dry mass of a plant as phosphate (actual 50-100%). Now, phosphate levels are generally thought to be sufficient at 1-2 ppm
or so, so it's safe to assume that the magnesium requirements would be 50-100% of that. As it turns out, the daily dose of Mg
in PPS is the same, about .1 ppm
, which is what you're seeing in the numbers you're generating. If you dose to 1 ppm
++ weekly, you should be covered; this is roughly .25 dGH. EI omits it largely because it assumes you're either dosing in tap water (good change of having decent Mg
) or are reconstituting RODI
(which will be adding Mg
). Either way, EI also includes Mg
in the CSM+B that would help offset this lacking if the need arose.
Interesting aside, one of the major CA
cities with an available water report had 50 ppm Mg
out of the tap. Yowza!