well, Whats wrong with my Plants!

UPDATE:

watering more often and with less volume.

I see the day humidity is staying low - around 40, humidifier coming tomorrow. Night is 60 as that's where my fan control point is set at.

Leaves dropping daily. Turning yellow but now they seem to be left with a purple color.

I upped the tiger bloom for 2 feedings to the recommended dose to ensure that i was getting them enough food as I mentioned I was really barely feeding them.

Previously this was only effecting the 2 older plants in 10 Gallon pots. Now the 5 gallon clones are showing the same way. I have 2 autoflowers in 5 gallon pots both looking great, IMO.

The buds look to be filling in despite the obvious. I wouldn't be too concerned if these plants had a short flower cycle but we still have approx 2 months to go.. I would be so happy if they finished early.

I don't think I missed any of the advice above. let me know if something was missed.

Help!

Hit them with some Epsom salt today. 2 teaspoons per gallon. 10 gal pots one liter each, 5 gallon pots about 1/2 liter each.

Humidity is back up to an acceptable range during lights on. Was at 50% today at 74 degrees. I actually think the low humidity was causing the severe drought look as when they got thirsty, it happened quick. As now they are responding much like they did for the most part of the grow. Still watering less more often.

we had a freak drop in outdoor humidity. Its super low comparative to the time of year. I'm expecting spring to hit any day now and I will be removing humidity.