Because they said so, lol.

I e-mailed them (Fox Farms) a couple of months ago asking if I needed to add micro's seperate from their formula. They said it (the 3-part system) has all the micro's you need, but they were almost too careful not to be specific.

So my thoughts are that it likely contains all of the micro's for throughout the grow. Would Kinda explain why using Big Bloom at half-dose is working so well for me, but since it's organic, perhaps it is just build-up if used too liberally. (like...at recommended dilution, lol)

I guess I could shoot 'em another e-mail asking more specific questions, tho.