From this pics alone I would say it's a ph lockout. The plants need to stay 5.5.-6.5 to see any new green growth. This plant will bounce back. Also, 90degree temps are way too high, so think about exhausting some of that heat. It has to be done.

Those two things alone will make your plant look like that. Also , what kind of "plant" bulbs are you using? Are you using "grow bulbs?" I have found the 6500K color temperature DAYLIGHT bulbs work much better as I think they are brighter and have a better color temperature for vegetative growth.

And by exhausting the heat from the room, probably by just leaving the room open will decrease your water temps as well giving you better results in what might seem as slow growth.

Like headshake asked, "Are you running a sealed room?"

And I'm curious as to what kind of ballasts you are running.