Serious problems 2 weeks in flower

[Cheeseking]

Hi everyone hope all is well, been away for a few weeks so plants are in the incapable hands of my partner lol. It's hard enough to get them to feed the plants! Sure some of you can relate I left just after they was flipped to 1212 looked nice and healthy and just got some pictures sent over today and getting some defincines.

I have added some photos below if I could get your opinions please and possibly a solution to get her sorted it has affected about 3/6 of the plants which are all the bigger ones of the grow

Soil, hydro or coco?: soil biobizz all mix

Strain: rqs cheese

Photo or Auto: photo

Plant age: 1st week flower (3 weeks true veg and 2 weeks stretch)

Pot size: 7.5l

Has it been repotted? and when?: 7.5l from start

Soil type: biobizz all mix

Nutes or additives used and how often for soil: canna vega used through veg with vitalink calmag at 0.5ml per litre once a week same through stretch and switched to canna flores after the stretch with calmag still at 0.5ml

Air temps (max min): 28 lights on max 18 lights off

Res temps (max min):

Humidity: stable 50/55 with it peaking to 65 during feeding day

Lighting type and wattage (hps, led, cfl):vegged under 400w mh and swapped to a 600w hps for stretch and flower

Light schedule: 18/6 before now 12/12

PH level: na

Usually feeding twice a week with a 3 day break in-between
for the wet dry cycle

[M_C]

Try dropping the calmag for the time being... soft water, I assume?

[Shaun]

Im not saying it is root bound but I had a plant look like that a month back or so, she was root bound and roots were actually coming out of the drain holes. I transplanted to a bigger pot and new soil and she turned around fast.

[M_C]

Pot size shouldn't really be too much of an issue...

[Cheeseking]

Thanks for the reply mc I'll get her to stop the calmag do you think this could be causing a lockout so will require a flush? And yes I'm in a relatively soft water zone.

And thanks for the reply stokes but I've always used 7.5l pots and been sweet as, I always thought roots "air prune" their selves like in the fancy air pots

[V8]

Hmm. To me she lookes underfed...

V8

[Cheeseking]

Yeah that did cross my mind v8 at first I thought it was a nitrogen def but it only started in the flip and was fed veg food all way through the 2 week stretch to boost them up. Its the black patches and the curling that really worries me I've never come across this before

[V8]

Do you have a EC or ppm meter?

V8

[Blue61]

Any chance they could be over watering? Looks like PH maybe out of wack also.

[mpsj]

Hmm. To me she lookes underfed...

V8

That be my guess.