Can you give us pics under regular incandescent light? It's hard to make out the coloration in those pics to try and figure out what the nutrient deficiencies/toxicities might be.
If you don't have the dough for a pH meter and a TDS meter, than with all honesty hydro is a really bad idea. Grow in soil. I'm not trying to be harsh, you're setting yourself up for all kinds of frustration and wasted effort--you have somewhat adverse conditions, and can't get the readings you need to make informed decisions. Hydro is not forgiving in that kind of situation, and can drive you crazy. But that's not going to help your current grow, so hopefully someone will be able to give you a decent diagnosis from the pics.
[edited: removed the bit about ducting, it's looking better in the newer pics.]
Random thoughts: In the future, you might consider smaller plants in micro scrog DWC using shared reservoirs to get the most out of the space. If you use two medium sized square-shaped reservoirs side by side , each with it's own screen, you could have two rotations in there at the same time--new clones starting and older ones nearing harvest. Of course, I'd avoid anything like that until you can track down those meters.
Anyway, here's hoping it all works out and you get through to harvest w/as little trouble as possible!