Light rules my ass...
every grow is different, back off the lights until the leaves perk back up
Yes your plants look like 1 of 3 problems
over water
over fert
or heat( also take a temp measurement in the root zone with a instant read therm)
I am guessing you have just barraged it with light. I say this as that is some righteous internode spacing. Once the leaves perk back up those will be fine. Also they could be slow rebounding from their early life trauma.
As a side note when measuring agricultural stress from light on farm animals what we used was a black painted metal toilet float with a probe thermometer
this modification allows for the effective measurement of the radiative, convective and conductive heat factors. (Note haven't used this since taking lab measurements for a course) but it is quite shocking how much the temp will change when using it vs a naked thermometer.
How are the plants doing?
Id say your best solution is to get vented hood that you can hook up to fan to pull 80-90% of the heat away from the bulb and allow for better light placement and eliminate/minimize heat problems.
To start, don't waste all that electricity on the 400w for the first week or 2. after a few grows, it adds up. I use a 175w HM w/hood & glass for 6 plants. it can get 1-2 inches away from the tops. Then i switch to a 400w MH when i feel it's time or they are ready (bushy, size, etc...).
for veg, MH keeps them short, HPS makes them stretch. but it can also be controlled if you have a HPS that contains a MH.
