It isnt just the organic vs synth discussion, UP your maxibloom to at least 5.5g per gallon and watch your plants come to life again but hurry!
Your currently starving them and killing the beneficial bacteria while probably flushing out the available nutes with weak solution, take my advice hit them with at least 5.5grams of maxi.
I wouldnt hit them with any salt until you know what the EC of your medium is.
Yellow and droopy sounds like salt stress to me...
In a way maxi can be good to get started even without meters (get them asap) because so much data is available.
https://www.icmag.com/ic/showthread.php?t=191645
Read thru that and youll get a good feel as to where your at.
my opinion 7g is too much at first so start them lower but go look at that thread tons of people with all mediums using maxibloom.