I don't know man... Cal/mg, are you sure??? I mean, it's important nutrient during veg, but NOT one of the big ones... I have such a hard time thinking that is the problem. But, I don't remember what type of nutes you're using...are they low on the cal/mg? In that case, I could totally understand it. And the leaves are showing what looks to be that type of problem when I look at the FAQ diagnoses chart...
But here's what I was thinking....
The wilting leaf problem....The ONLY thing i can think of is lack of oxygen to the roots. You've ruled out almost everything else. Yet, your system should be delivering enough oxygen with the setup you have going. My figuring is that during sleep they need less, and so they bounce back. and then 3/4 of the way through the light cycle, they aren't getting what they need. at the same time I was thinking that while they suffer for the oxygen they need, it's causing a problem with nitrogen getting to the plant as well, and thus the browning of the leaves.
Now, I'm no expert problem diagnoser....this is just the thoughts I've been having. I've been thinking about your problem a lot more than you probably know, dude. I want to see you have a VERY successful fucking incredible grow!!!
Anyways, I will continue to research your problem and I hope that between every one at this site, we can get it whipped!!! Until then I think you should go ahead and try the cal/mg and see where that gets you....Maybe that is it. Let's hope so, brutha!
-S