Rockwool and nft

[Rio_Grande]

I have a downspout nft system as it turns out some of the net pots I ordered are shorter than others. I tried to get the rockwool back out of the cup but was destroying the seedlings doing so. Instead I put a 1/4 in thick bead of calk in the end of my trough to form a dam of sorts. Now all the rockwool touch water. I know there is a dichotomy between those who think it should touch and those who think it shouldn't. I don't have any roots out the sides of the cup yet and the water isint turbulent enough without the dam to get the cups moist.

Is there any issue with having the rw touching all the time that are going to cause this to not work? I figure as soon as I get roots hanging down i will move them to rails without a dam.

I have aeration in the tank, but not in the rail.