I start my seeds in rockwool......

I am doing a hydro set up. I start my seeds in RW then they are going in Net Pots for a vertical grow. They germ fine, but then they stretch to 3 inches within a couple days. I am using 2 T5 setting right down on top of my propagation tray lid. Help?

Sounds like your genetics is why its stretching, not much you can do other than top it!