My guess is its 2 separate issues. The spots are from splattering water and or nutrient on plant, the edges on leaves burning is from the light. 800 something watts isn't much for 9 plants however they are young plants that may be too much too soon. This plant had light intensity issues looks like your leaves edges. Light could be too close for amount of wattage used and plant age. Personally I'll run 50% until flower. It doesn't take much to veg especially if you have a quality light with good canopy penetration.