Each set of "twins" came up from one seed. (Or what looked like one seed anyway.) *Can* I even separate them? How? I've never pricked apart seedlings before. I'm afraid of breaking them. Any advice on how to go about it? I had decided to just give up and accept they'd be stunted...
I lowered the light with the new bulbs to the same height as the old one. The lights are still higher above the seedlings than before, about 4". The seedlings used to be on upside down trays which boosted them up a couple inches...they are now in those (now right side up) trays. Next time they need watering I will be watering from the bottom with plain water.
Unless someone tells me different I'm going to assume the odd, acetone smell was because those particular plants were *especially* too wet. Maybe they had a little bit of root rot that I couldn't see. Hope they manage to recover now.