I always use about 1- 2 ml molasses : 1 Liter wasser/feed. Gradually increasing throughout the plants short life. That would be roughly 1 - 2 Tbsp per Gallon. I love the molasses, for some reason. I am loving this ER that's been curing for 4 weeks. I used molasses from about day 3 till the very end and I'm sure it did something for the flavor. It's a sweet inhale and after exhale it's an aftertaste as if your sucking on a thick sweet candy drop. Very good stuff. I's going to harden up the top layer of soil after feeding. It dries and "crystallizes" the top layer, so you have to always loosen that up before feeding or watering again.
The new box is the one you're building, right? You're going to go with flat white paint? After you get it all finished, try to get the paint as dry as you can before putting your plants inside. Use a heater on high or a halogen construction light or something that will dry the paint quick. Otherwise, you'll have a bitch of a time with humidity till it's all dry. I only have this small cab and some pretty good ventilation, but till the paint dried completely, I was fighting with RH and was very worried that my newly forming nugs were going to suffer.
And if you use caulking, make sure you check it after everything's dry, before you have all your wires and lights and everything else setup. It would suck if you have to take it all back out to fix up the caulking.
Mine was probably cheap stuff and it opened up in a few places. It didn't really bother me that much cuz I had my lights on 24/0 and I didn't have to worry about light leaks. It just looked un-stealthy because light was shining out through a few cracks where the caulking opened up.