Autopot plants lime green with brown spots

Hi i have 4 plants in autopots and they have taken on a lime green/ yellow look with some brown spotting on the leaves. My first guess is calcium deficiency but i am feeding calmag at half strength along side already using tap water so is this some sort of lockout issue? Any input would be appreciated.
medium is plagron 60/40 coco clay pebbles
Ec feeding is 1.4
Ph at the autopot valves is 5.9

The bigger 2 at the back seem much healthier and green and don’t appear to have this issue

Magnesium deficiency and I see what’s likely potassium deficiency developing.

hotrodharley said:

Magnesium deficiency and I see what’s likely potassium deficiency developing.

Click to expand...

Okay so why do you think that is? Don’t think ec is low for stage of growth and they are being fed calmag at half strength. Could it be a problem at the rootzone possibly?

Marcorfl said:

Okay so why do you think that is? Don’t think ec is low for stage of growth and they are being fed calmag at half strength. Could it be a problem at the rootzone possibly?

Click to expand...

Are you using tap water?

hotrodharley said:

Are you using tap water?

Click to expand...

Yes am using tap water with a background ec of 0.4 and feeding calmag 1/2-1/3 the strength

I am using tap water in my separate dwc grow with no issues

I don’t use coco or coco mix mediums. But in Pro Mix I only give cal mag routinely during the first 4-5 weeks of bloom. I use municipal water.

hotrodharley said:

I don’t use coco or coco mix mediums. But in Pro Mix I only give cal mag routinely during the first 4-5 weeks of bloom. I use municipal water.

Click to expand...

Okay I’ll wait to see if anyone else has an input. Potentially its a lockout issue maybe. I may turn the res off for a day or two for a break from the system

Anyone have any remedies for this? Up the feed or anything else. As you can see the 2 at the back are definitely greener than the front 2. All appear to have purple/ green stems with the front 2 being most affected

Update on issue as still not fixed. Being autopots ive read that lower EC is the way forward so I lowered overall ec and upped calmag from 75% to full strength 1ml per litre with an ec of 1.1 but no signs of improvement…
Any advice on steps to take would be appreciated. Flipped to flower a couple days ago as they as getting big so hoping to get this sorted soon