You feed jacks321 everyday?
Had exactly the same thing happen with two grows in a row when I started using Jacks 321.
First ditch the cal/mag. Part B is Calcium Nitrate and as soon as its dissolved it becomes Calcium and Nitrogen. Epsom salt is Magnesium Sulfate and becomes Sulfur and Magnesium once dissolved. You don’t need calmag, I never use it anymore. If you see the burned edges and tips you need to back off the nutes. I also grow in coco and when I see the first sign of edge burn I water with plain water a day and then 1/2 strength for 2 or 3 days. Once its been arrested you can resume full strength with a plain water once a week. Not every plant is sensitive to full strength Jacks but some are. And it will start on the leaves closest to the lights.
Indeed, that’s my coco schedule
Will give this a go
With Jack’s you can adjust one of the three parts to handle any deficiency. I raised part b by 0.2 grams to deal with a calcium deficiency. I’ve seen others adjust the Epsom by 0.2 to deal with magnesium deficiency. Seems like adjusting by 0.2 g is a pretty standard first move. I’d always recommend making sure pH is correct before adjusting the formula, but you already did that.
Just for my own info are you using the standard 3.6/2.4/1.2 or the new recommend formula 3.79/2.52/0.99? Any water that goes into your coco should have nutes in it according to Dr. Coco. From one of your earlier comments I couldn’t tell if you’re giving Jack’s then water the next day or just Jack’s EOD. I feed every day in coco to runoff no matter what.
That fuzzy stuff on the pots scared me this grow. I thought it was mold or something. I cleaned it off a couple times then just let it ride. It’s no cause for concern.
3.6/2.4/1.2, I feed everyday.
PH, magnesium or both. What’s your input and run off PH? Bump up part B to 1.5 and the deficiency will take some time. What medium are you using read up and see it’s coco, PH range of 5.8-6.0 in Veg and 6.0-6.2 in flower is what I follow and to liberal run off