Sporadic browning and curling upward

[BigRedRussian]

Hey all,

Back again with another problem. Leaves are curling upward and browning in no particular pattern. Almost like a sunburn.

Growing in coco, currently week 6 in bloom.
Using AN sensi range with b52,bud candy, overdrive, calmag, big bud all at half doses the whole way through with great results up until this point.

Feeding EC 1.4-1.6
Runoff is ph 5.3-5.4
Lights 2 x Sk402 + 600w vipaspectra in a 2.4 x 1.2 tent
Rh 50-60%
Temps lights on 29c
Temps lights off 23c
Lights distance is approx 40cm
Only one of three plants showing signs happens to be one under vipaspectra.

Check the pics see if you can shed any light on the situation thinking maybe the cheap led is potentially more potent on the UV or could it be something else.?

 

[Heavenly Hybrid]

I’m no expert, so certainly see what other say. To me, that runoff seems like it might be to low and causing some nutrient lock out. I’d think if it was from the light, you’d see damage at the tops, and your buds are looking great. The ideal pH going in is 5.8-6.0 in coco. Good luck and welcome to 420 mag!