Hey good luck with ur grow stretching is usual a sign of the light is too far . Dwc . Hydro is the best every . I’ve now moved onto the nutriculture I have simple blocks
They stretch when they want more light. Move the light a little closer and they should stop. And rockwool is a pretty tricky grow medium to start in. Definitely let it dry out quite a bit before watering and just dip half the cube in nutrient solution when you do water them. Good luck!