why are my leaves curling (PIC'S)

what would couse the leaves to curl up like this any info would be great they are 3 weeks old and i have them on 1/4 strengh gh nute's i dont think its the temps im thinking its a nute problem from what i diagnosed its likely to be from b (boric acid) but im not sure.

spec's
strain-g-13
system-dwc hydro
nutes-gh flora series
3 weeks old from seed
light-400 watt mh 24-7
temp's-83 degrees

how close to the lights are they

Looks like heat stress to me.

My plants were doing the same thing. I moved them further away from the lights and turned fan speed down problem was resolved.

MY leaves are droopin I have a 1000 watt lamp about 3 - 4 feet away from the plants with fans so its around 78 dagrees. But when I first put them in, the light was 1 1/2 feet or so away from the plants !!!! ????????????? im thinkin heat stress?