Please help my seedling are dying

HELLO rollitup i need help real bad my seedling are dying i don't know why the are about 2 weeks old there are in ffof soil with i think is burning them somebody told me to flush them i did no change my ph was low around 5.5 i brought it up to 6.3 they are under a t5 light . Check out the pics i know its somebody out there that can help me I havent used any nutes yet just ph adjuted water.I water every 3 to 4 days