Yellow patches on leaves

[MrCog]

Hello,

Please could somebody help me identify this? I'm colorblind, so although I have looked at many other people's pictures, I'm struggling to match the symptoms on my leaves.

For info:
Strain - Barneys Farm Blue Cheese.
600w hps - air cooled hood, 40cm from canopy.
Oscillating tower fan was pointing directly at them, now it is facing wall to bounce wind off.
Daytime temps: 25-26C
Nighttime temps: 16-18C
Humidity: 55% - rises to 80% during lights off.
2nd week of vegging.
Biobizz all mix soil.
Biogrow nutrients (using 1ml per 1litre). I water until the saucer is full of run-off and drain it away, then let pots dry until at least top inch of soil is dry and pots feel light before next watering.

I've noticed some of the leaves "clawing" which makes me think nutrient burn - and read that this particular strain suffers from nutrient burn quite easily. Also seen some of the leaves folding/cupping, so I raised the lights a little.

Any help is greatly appreciated.