Don't pluck them . . . cut them off.

Can you give me more details on how you planted in rockwool. Did you use the 1" x 1" cubes with the hole in the center? If so, did you put ONLY the seeds in the hole or did you cover them with something?
Everytime I start in rockwool they come out very leggy and thin.
Thanks.

Yeah, don't pull seedlings to remove them, you can accidentally pull their neighbors out too, or damage their roots.

I'd recommend getting a little tin like Altoids mints comes in, fold a piece of paper towel in it, moisten it, and then put your seeds in there. Keeps the dark and wet, just like seeds like to be. Most seeds, anyway.

Then transfer the seeds to the rockwool once the tap root has appeared. Once seed per cube, since you won't see too many failures after the root comes out (as long as you don't damage it in the transfer).

Oh, and I wouldn't feed a seedling any nutrients until its started growing its first set of true leaves.

This is my first hydro crop, and is a learning experience. I've already done plenty wrong.

I dropped approx 5 seeds in each 1" rockwool cubes, then put them in a tray of water. I didn't realize I should have soaked the rockwool before planting.

The seeds sprouted in about 3 days, and just like hinzy said, they seem leggy and thin.

Planted them in 3" baskets with hydroton around them. I put 6 of them in the ebb and flood system right away, and held 6 back to grow a bit more.

The 6 I held back I PULLED the extra seedlings out this afternoon. I will have to go out to the hydro garden tomorrow and snip the extras from the other 6.

Thanks for all your suggestions.

I seed directly into the final container. My ebb-n-flow uses coarse gravel mixed with perlite in a 1:1 ratio. When I seed, I wrap a tablespoon of perlite in some tissue paper and place it on the high water line inside a container. Then I puncture a hole in the wrapping to the correct depth and drop a seed in it.
I've never had any trouble with this.