sorry to tell u but 2000 watts wont be enough for 36 plants 4by4 is best for 1000 watts i have 13 under 2000 watts and it aint enough i need at least one more 1000 watt
check out my link https://www.rollitup.org/indoor-growing/439366-barneys-pineapple-chunk-greenhouse-cheese.html
i keep my light 2-5 inches from the plant you will love the results place fans just under the light to keep air moving