Soilless flower outdoor problems

Hello,

Outdoor grow
Coco soil less
Feed GH flora series with cal-Mag
everyday 4 gallons of tap water per pot about 20/30% run off

Cal-mag 1/2 tsp per gallon
Flora micro 1/2 tsp per gallon
Flora bloom 1/2 tsp per gallon
Flora grow 1/4 tsp per gallon
Feed at 5.8 PH

Little back ground my plants have been nothing but prefect that actually grew to good and I ended up having to drop the 25 gallon fabric pot into the ground as they are over 8ft.

They have now been flowering into week 3 and are starting to show signs of what I think is mag issue.
we have had a supper bad heat wave the last few weeks with the high in the grow area at 103f with 43% hum.

Some of the plants the sativa seem to be doing better however all of the plants are starting to show this yellowing that seems to start at the bottom and working it’s way quickly to the top.

Just wanted to see if someone could help me out

So surprised to see someone with the same issue.
Coco is only a 17-18% component of my soilless mix, but I had the exact same problem when the heat got up. Up until then I had stellar looking plants. Like yours, some were affected more than others. That edge burning that looks like a potassium deficiency probably isn't at all but is exactly what mine showed as well.
I have managed to get out of trouble and back on track (with quite a bit of leaf loss from one plant), by really watering heavily with about 1 tsp per gallon epsom salts and some unsulfered blackstrap molasses. I also top dressed (1 TBSP on a 10 gallon fabric pot) with some kelp meal for a potassium source and Gaia Green power bloom (2 tsp).

The most important of the above seemed to be the heavy watering with the Epsom salts just to flush out whatever was creating the problem.

I have no idea if this will help you, but there are some major similarities in our situation.

Let us know how you do.

cannaloop

Update:

I was able to test the run off on some of the smaller pots I was getting about 6.1 run off from the 15 gallon pots.

All of the pants seem to be doing better except for one the Alaskan blue she is really not happy and the break out is almost to the top of the plant.

Not sure what to do with her. I did notice as I was looking around the other day a bunch of these little bugs that sit on the main stock never find them on the leaves. They seem to be shooting what I think was eggs out of them. I did notice a few on the other plants but nothing like this one. I do not think it’s the cause but thought I would post it.