Okay, I need to fess up. I DO indeed have heavy chlorine here, but that was most likely NOT the cause of the seedling issues. I apparently had grabbed the wrong soil when I re-potted. I used composted cow manure with worm castings added, instead of the plain cow manure. The little buggers were OD'ing on Nitrogen, I believe.

Believe it or not, adding Eco Bloom (heavy in phosphorous) on top for 2 waterings brought them back around, although they seem to have lost a few weeks of growth. The sicker ones I carefully "root cleaned" and re-potted in FF Happy Frog. All but one survived.

Thanks for the posts, all.