Your grow area is a lot like mine, I will be watching because I want to have as much success as you didMy growing space is about 3'6"x4' and I have a lot of vertical room. I have them all packed together pretty tightly as you can see in the picture below. I'm hoping I get an oz per plant as well.
I think that having a TDS meter and PH meter are the two most important items in a grower's toolbox.No I don't have a TDS meter. Wow the thought of possibly having 280grams is making my mouth water . I've never had that much weed at one time. I guess it's time I purchase a new bong to help me go through this.
To my knowledge grow big and tigerbloom are bose NON organic, while big bloom is organic. FF does have a lot of organic stuff (peace of mind and such) along with their soils. Open sesame, beastie budz, and cha ching aren't organic either I think, not sure about them though. Even if they're not organic they're gonna have some organic substances in them probably though.I disagree. Fox Farm nutes are organic! Earthworm castings, Norwegian kelp, bat dodo, all that good stuff. That don't sound chemical to me.
As to question from enjoikr3w, NO no nutes after flush. Flush should be with room temp water and 2 to 3 times the volume of the soil. Blow the bad stuff out, let her recoup (although I don't think you need to) and then start nutes again. From what I understand, it ain't a bad idea to flush every month.
I doubt you have an overfert problem (I should know, I had one DUH). As for the yellowing of the lower leaves, that's normal. They are really nice ladies. I'd stay the course and do as you are doing.
If you really think your underfeeding, kick up the nutes a tad and watch the girls. They will let you know.