Been waiting for a hydro guru to answer, but I guess they are...unavailable.

I'm no hydro guy, but looking over your troubleshooting form, I'd quit the carbonated water, lower humidity and just use your nutes as directed till you figure it out. Most hydro nutrients programs have all you need, so you might want to stop with the additives, as they might be adding to a lockout situation where the plant can't uptake anything. Once you figure out the stress, perhaps you could resume their use, unless they are the cause.

The carbonated water clogs the pores, and is the likely source of the duskiness and the powdery shit. Rinse all the leaves off with a gentle spray (top and undersides) with properly ph'd water. The sugars in the carbonated water makes everything sticky, and attracts bugs, too. Not worth the impercievable benefit, if any.

More air circulation, and/or less spraying/fogging. When flowering, you'll want to keep the humidity levels down to avoid bud rot and mold.

Also, is 24" as close as you can get the bat-wing? Since she's stressed right now, it's likely a good idea to raise it a tad, but is that normally where you keep them? (sounds kinda far)

Hopefully someone with hydro experience will come along to offer advise about your levels and schedules and such.

Good luck.