No wonder it is too bright to look at. Ten bulbs! All 40W? Ten in each? That's a massive amount of light.

The only issues I can see with the design (apart from maybe needing to turn off half the tubes!) is lack of air movement. The enclosed system works great for cacti, but not so well for some plants. Your fans should do the trick. It will be a bit of trial and error to get the temperature adjusted.

The chains might be overkill with this design. In a completely enclosed box, the height of the light makes very little difference to the intensity. The only variation I've found is when some plants are raised and some are left lower, then the raised plants get slightly more intense light and shade the lower ones a bit.

Hi shrubs,
It is 10 bulbs, 40 watts. The temps are not bad since switching back to standard fixtures. The fans exhaust the air space above the lamps . I did lower the lights when the plants were tiny, but brought them back up. It is a lot easier watering with the extra distance between the bulb and plants.

What is the drawback of excess light? I've been leaving the lights on 16hrs.
Dave

Wow! Which prize seedlings will you put in there? They'd have to be special to get the light box treatment. I know in my light setup, it is never an cosmo or marigold that gets the overdriven fixtures. Nice!

Looks good to me..! If your doing primarily vegies, your light box should get them off to a good start. Just check them everyday and adjust as needed....

good growin'...