Help! My Seedlings are Need Serious Advice!

Sorry man I'm new here.... Ok I'm 2 weeks into growing white widow, setup: reservoir(ebb n flow) 600wt mh lighting with 1 flouresents light on each side of the system... Temp is always between 75-80 degrees... Watering with light nute solution for like a week until I saw them dying now I used carbonated water and distilled water 3 times daily... Using rapid rooter as my medium....Oh my nutes are: general hydroponics florabloom, floragrow, and flora micro...I need help man can someone Please!!!!!! Thx