I'm a bit of a failure when it comes to starting seeds in rockwool i'm afraid, i have to grow em in soil etc then clone em, at that point they can go in dwc. Either that or i just wash all the soil off and tape it to a net pot.
As it is though here's what you do.
To germ the seed, i've found with rockwool that you can't germ it and then easily insert it, unless rockwool is cut in half and then rubber banded back together, so easier on the whole to just drop it in. You then have the option of germinating it in a prop etc, or in a dwc tub, either way, you just gotta keep a sharp eye on the moisture level of the rockwol, not too wet but not too dry, you should not be able to shake water out but if you pinch two corners gently it should drip water.
To germ it in a dwc tub, you can either use feeder tubes and a submerged pump and drip feed it, or you use the bubbles to keep it wet, which involves monitering the water level, too high and it'll be too wet, too low too dry. Alternatively a more or less powerful pump or the placement of the airstone etc. When doing it this way, it pays to have a second net cup and rockwool cube setup, just as a benchmark cube, run the tub for a few days with the test cube and you'll find your water level wihtout wasting seeds.
Then just keep the rockwool this level of dampness until roots are in the water, after that it doesn't matter one bit how wet the rockwool cube is really.
Not much of a "thread" but i can answer questions as they're asked haha/ If not i think it was illegal smile that had a very good DWC thread about DWC without the tubes.
As i say, i've always done clones in the past with no issue, seeds slightly more, probably due to my lack of attention, i gto 2 lemon skunks to turn into seedlings just fine and then i killed them y forgetting a humidity dome for a few hours. If using a heated propogator, a dome is essential, the cubes will dry out in hours. and everything will goto shit very very fast.