Hydroponic Sproutlings Burning up?

I'm kinda new to hydroponics. I started seedlings in cubes and watered them when needed. I put the cubes on a tray so that the cubes would absorb the water from it, They began to sprout normally, but after a week or so, they seemed to stop growing and start drying up. I'm using florescent lights instead of a MH so that they don't get too hot when they sprout. I keep the PH level of the water at 5.8. I have no idea what the problem is, any suggestions? Or maybe a short guide on how to start hydro seedlings. Thank you.

pics would be helpful

could be overwatering or nitrogen deficiency though. Rockwool cubes have no nutrient content so this could be your issue

yeah I havn't been using any nutrients. I thought that early using them could harm the plant that early.