One post per topic please.
Is your HPS air cooled?
You have to ventilate well to get rid of paint fumes before adding plants.
How long did you rung the HPS before taking temp measurements?
How tall are your waterfarm units? Are they actual Waterfarms that stand ~14" high? 4 feet headspace, minus a foot for the light, minus 14" for the buckets, minus the 18" you need between a HPS 400 and the canopy, leaves four inches for the plants.

Try a SOG on the floor of the box, using newly-rooted clones in 6" quart pots, the short style, not the tall deep ones.
stinkyattic Reviewed by stinkyattic on . What do you think Here??s my set-up two grow boxes each is 4?? tall 2??wide and 2?? deep. That is 4?? square feet and 16 cubic feet of volume. The lighting I am using is in the veg box a set of 2 175W MH and in the flower box I??m using 400W HPS. These boxes are painted white ( five coats) on the inside and a water sealer has been copiasly applied. To start off with the boxes are air tight. To build the boxes Materials at Home Depot 5 4?? x 2?? ½?MDF Screws (I used 2? #8 screws), Rating: 5