Drooping leaves problem

Grow style: aeroponic/DWC in 5 gallon bucket
Light: 90 watt LED
Height: about 18 inches from plant
Nutes: Technaflora Recipe for success

I'm a total newb doing my first med grow. The problem started a couple days ago I think, I know there has been a little heat stress, it got up to 82 in the tent (I keep it open) most days it's between 75-79. I noticed the first set of lower leaves drooping maybe two days ago, did a res change yesterday, added about a gallon and a half of filter water, the plant is about two and a half weeks hold.

Fed yesterday 9/21/15
per six liters:
boost 5ml
grow 2.5 ml
thrive (red) 1ml
magical 1.5ml
sugar daddy 4ml
Total PPM after nutes but before adjusting PH was 391, it's about a quarter of the strength recommended.

I think the droop started right after the roots actually hit the water before that they were suspended in air. As soon as the roots hit the water I added an air stone to the bucket. Oddly the roots in water are pure white whereas the roots that are suspended have a slight brown tinge to them, some of the newer growth is white too.

This morning I thought it might be root rot so I added 30ml of hydrogen peroxide and they started drooping even more, so I filled a bucket with tap water PHed it and threw it in a pure DWC, now it looks worst LOL I don't have a pic of that since my camera is dead.

I don't care if I save this plant or not, I just want to know for the future so I don't make the same mistake!

I appretiate any help or tips!!!

Light is too close most likely.Back off about 8". They will adjust then you can get it closer. Get your PPM down to closer to 300. Otherwise it sounds like a good start. Good luck.

Thanks for the help. I backed it off and they seem to be doing better, it could be a couple problems, it stays between 73-75 so I don't think it's a heat problem, the PH might of been too high or I might have root rot. The roots are a brownish color, I'm not sure it's the nutrients I'm using, I'm getting a decent amount of new root growth that is white so I'm going to monitor my PH and see if the roots get any darker.

It looks fine to me. Some strains grow with leaves that droop, and some point straight at the light.