Rockwool cubes in hydroton...should they be wet?

Hey guys,
Quick question.

I just recently moved my rooted clones in rockwool cubes to my ebb and flow trays which are filled with hydroton.

The roots are coming out the bottom of the rockwool cubes, but only a small amount. I have two options- I can 1.) set the rockwool cubes on top of the hydroton (only buried a small amount) so that the roots can reach the water when the table floods yet the rockwool remains completely dry or 2.) set the rockwool slightly deeper, so they also contact the water when it rises.

I have read that you do not want the rockwool to be in contact with the water cause it wicks up too much moisture and can cause root rot. However, as I have them now the cubes are almost completely dried up, and I wasn't sure if that was okay either.


I'm using 3 8 minute floods during lights on.


Thanks!

I would set them so a 1/4th of the cube is in the flood line

I have it just above the water line. Lost a plant to stem rot my first go and nothing since.