Grundle said:

This looks like you are having VPD (Vapor Pressure Deficit) issues caused by less than ideal humidity (if I had to guess). This same situation happened to me and took me a long time to figure out. When this happens the plant uptakes more water along with nutrients because the lack of vapor pressure (humidity) in the air is causing increased transpiration. This leads to nutrient lockout and you end up seeing purple stems, slow growth and yellowing between the veins of the leaf. You may also see the leaves getting rough and have a puffy appearance between the veins. I copied a link below that has more information and VPD charts but there are a lot of online resources for this issue. What I did to solve it was to dim the lights a bit and increase the humidity to 65% until I saw normal growth again, Based on my own experience, it was not worth the effort because it took many weeks to resolve and when I put the plants into flower, they still struggled a bit. If I were to run into this issue again, I might be tempted to trash the grow and start over. I could be wrong but this is what I think is happening here.

Vapor Pressure Deficit - The Ultimate Guide - Dimlux Lighting - The Best Grow Lights

Simply put, Vapor Pressure Deficit measures the difference between the amount of drying power the atmosphere is exerting upon your plants. VPD is the key...

www.dimluxlighting.com

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kyle57843 said:

Idk what is going on with my plants been a while since I've had any problems but then this shit starts happening to all my plants started in early veg I'm getting super slow growth and wierd yellowing of leafs though after flip it would change but nope been progessing. Using the full floraflex nutrient lineup recommended dosage, powersi, and calmag. This is beginning flower. I also use floraflex coco. Feeding at 1250ppm coming put at 1280 ppm feeding at 5.9-6.0 p.h.this also happening from the all over the plants from top to bottom

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MasterCookie said:

You also have a magnesium.. Calcium.. and phosphorus deficiency. At to low of a ph Calcium can actually still bind to phosphorus and precipitate.. people who run lower ppm will not have really show this up.. but higher ppm together with water loss via evaporation on the coco surface can further concentrate the nutes at the root zone. Your plant is stressed so it will not be uptaking mineral optimally.. so much of your water loss will be to normal evaporation and not due to plant transpiration.

So do a flush with a lower ppm nutes and buffer your ph up a bit to ph6. It seems like your coco isn't charged with Calcium or magnesium because usually runoff water is usually higher than input water.. unless you nutes have higher amounts of Nitrogen in the form of Ammonia.

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