inverse square laws says 1 foot from a single point of light that it drops to 25% full lumens there...so a 1k at 1 foot away is now only a 500 watt light, but in hoods we do get about 24 inch for a 1k. a 600 is about 22 inch and 400 is about 18 inch. so a 600 is what i run and keep about 8 to 12 inches away for best use of the light. if its to hot then you need bigger better fans.
check the ph to fix it. i havent seen anything sayin what ph your at, your food should be about 600 to 800ppm id guess for that size of a plant