HELP my WW is in trouble!!! PICS

Hey guys, I recently started a project involving 10 WW that i got from Nirvana and i'm about 3 weeks in to veg.
I'm currently running them under 600watt hps setup and the temperature is constant fluctuates from (70-77) 4 of them have died off and I'm left with 6. However, I seem to be having some issues with them.. I'm not sure whether it's a nute lockup or what but I've tried flushing them but no results. so please g help me out people of roll it up.. criticism and opinions are appreciated.

Here are some pics of my problem

Way too much fertilizer bro...Especially nitrogen.

Or your light is hanging too low and the bulb burning the tops..

How often are you watering? I'm thinkin too often..

I'm using regular fox farm ocean forest and I added 1/3 the amount of some happy frog fert.. I'm watering every 4days.. I water about 2 quarts ( I have 3 gal pots)

Add some gardenlime,water when the pots are dry,you can tell by picking them up.78F day,is perfect,night 68F is perfect.Always add gardenlime to the mix,if none is in included in the pottin-mix.Heres the best lime on the market http://www.google.com/products?hl=en&source=hp&q=espoma+garden+lime&um=1&ie=UTF-8&ei=sf6eS_yoFZCwsgP7zYCRCw&sa=X&oi=product_result_group&ct=title&resnum=1&ved=0CBgQrQQwAA if theres nutes already in the mix,wait until the plants are 1 1\2 -2 months old, too add more nutes.

what can I do to fix the problem? just keep flushing?