Leaves are yellowing

[jby]

First week of flower, start to have the same problem.
General hydroponic 3parts bloom 9ml micro 6ml and grow 3ml per gallon, 2ml calmg, 1ml super thrive, 2ml kook bloom, 900-1000 ppm, flood and drain system, flood 2x everyday and 10 mins every time, 8x8x8 coco cube, in/out to exchange cool air. Some lady is very healthy, there were like 8 out of 55 look sick.

 

[mfed]

look like nutrient burn

 

[youngOG]

flood and drain is ok with coco ... but you have to do periodic hand watering by the top to rinse the salt accumulations
when you medium dry out the mineral fert will cristallize and be trapped in the top layer of your media, and if you dont counter act by rinsing them often, they will burn your plant and create deficiencies ( excess of some nutrients will block the others)

feed around 1.5 mS and be sure to measure and runoff=feed
meaning you want the water driping under your pots to be at 1.5 too ..
i guess that if you measure it now the runoff will be crazy high

my 2 cents