A 400w I wouldn't keep any further than 8-12" away from the canopy, the lower end of that is for an air cooled hood with a lens.
And my bad, that plant is in mostly Happy Frog that has been amended a bit. Ocean Forest-based mix next transplant. Ocean Forest has more nutrients in it than Happy Frog (alone).
So basically started in Happy Frog with dolomite and kelp meal. Mainly water the first couple weeks, but small amounts (1/4 tsp Bio-Root and Bio-Weed per gallon). Mostly just Bio-Root (5 ml) then some Bio-Marine at 2.5 ml and later at 5 ml along with the Diamond Black (humic acids) at 2.5 ml, these are all half gallons but still pretty low rates.
Then it was transplanted into another HF based mix, more heavily amended with coco coir, humus, dolomite lime, eggshell flour, Azomite, Espoma Citrus-Tone (5-2-6) and a little bit more Kelp meal. An inch of OF was placed at the bottom of each container, I didn't have enough to use it for the base. Had I more Ocean Forest I might have laid off the Citrus-Tone until next transplant. After transplant they are again given basically just Bio-Root and sometimes Hi-Brix molasses. Then the teas begin for foliar and drench applications every now and then.