You were getting up to the 90s with that big ass fan house fan in the top? I'm doing a rubbermaid set up too. How many CFLs do you have in there? I've got 5 in mine right now, with just a little computer fan to cool it, and I'm still around 82 usually. I haven't stacked my tubs yet, I was just planning on getting another fan. I figure double the box size and double the fan. Now I'm thinking that it might now be enough?

As for the discoloration, I looked it up in my new library, and it says its one of two things, too high heat or chemical burn, so I'm guessing its too high heat, though I can't attest to your nutrient mixture.

Man, your plants are pretty crazy looking! Any idea what strain you got going there? The one in the top right looks more like a mushroom, and the middle one reminds me of a rosebud.