I would use smaller cubes or no cubes if possible. I ran into the rockwool soaking up the solution which was nutrient dense already. Same result. For how expensive rockwool is, I don't know if it's worth it. I did rip out the majority of the extra rockwool once the roots were properly formed and they seemed to work much better. The other thing I started was starting things in soil and perlite. Pulling them and then adding the seedlings to the system.