Yeah, mixing concentrated ferts for 30 gallons in only three gallons of water isn't a good idea. That's why 2 and 3-part ferts are in seperate bottles, if they were in one bottle the chemicals could bond with each other and fall out of suspension. Not sure if it's true about a particular order they are meant to be mixed, I've read that in mags and on the internet. Read one article that said you should add the one with the most P in it first, because in hydro the P is what helps buffer the PH. I don't recall any fert company stating that they should be mixed in a certain order, just to add them one at a time until fully mixed then add the next.
I've seen Florashield, but never tried it. After reading a description of it, it sounds a lot like what adding peroxide to your res. does for you. Your drying them to the right point, not brittle but not wet either, I prefer mine a little more on the dry side though, but that is just me.
One of the reasons I went back to basics with K.I.S.S. is it seemed like the more products I used the more problems I had and would run in circles trying to figure what was the culprit for any particular problem. I was using the lucas (bullshit) formula GH 3-part, cal/mag+, floralicous plus, florablend, and koolbloom. Now I just use RO water and GH 3-part mixing according to the directions, the ppm's come out around 1050 and adjust the PH. That's it and no problems what-so-ever, I check the PH everyday, but I typically don't even have to adjust it unless I've added back a lot of top off water. Sometimes less is more. Not to say I'm settled with the results, there is room for improvement, I may start adding the floralicous plus again.
You're using AN 3-part, anything else? You're using tap water too right, what is the ppm's of your tap water? Just wondering because your ppm's seem high to me, but I have seen plenty of strains handle more that that. You may have to consider that differents plants have different nutrient requirements, which could be why your BG's are fine but your other strains are hurting. Glad to help.