hydroponic tips

I have 2 babies now 2 weeks old. I started them in 1.5" rockwool til the roots came out then went to 4x4x2.5 rockwool, now the roots are coming out the bottoms of them too! My issue is, I currently have them under lights (300 watt LED) on top of the Gro-Smart tray I got from Grodan. Can I go...