Ok....spoke to my hydro guy. First he had several questions....one, did it happen to get very cold in there at some point? Or did your fan fail/ventilation system fail at all in some way? If you are using a spray (aero) make sure all your sprayers are working properly. If your watering system is on a timer, did the timer fail and the plant get overwatered? Check roots for root rot. Check your timers and make sure they are all working correctly.

If all those are a negative...he said you'll simply have to try things step by step and see what works since different conditions can appear quite similar.

The first step he suggested was to up your CalMag. Told me to have you take up 200 ppms .....(say to 400?) and see if any changes. If that didn't work I'm to call him back.

Deja understand that these are your plants. (i know you know that) You are there with them and you are the one who's going to be stuck with dead plants if you follow my info and it is wrong. If your gut is telling you something else you should strongly consider that....again....your plants.....you must make the decision.