my babies are not looking to well

my three week old plants are turning putple/brown on th etips of leaves.. the light is a 1000 mh and is positioned 3 or more feet from the tops of the plants

did you flush your coco first. i got screwed and didn't know better with some coco mats and it ph'd so hi it burned my roots off. check ph of whats coming out of bags! most manufactures they say they're flushed but do it again anyways

hmm so the water turning brown is bad? lol .. thanks alot man ... is using coco in an ebb and flood system a bad choice .. or would i be better off with hydroton?
well just a newbie learnin so any help is appreciated - thanks man

early stages of room setup nothing finalized ...