Hi there Domaintraveler, i gotta disagree with my growmie odrex on this one, the seedlings cant be rootbound at this stage : they're just too small. What happened is that there was overwatering that caused root issues. So it's really easy to overwater seedlings like that because the plant doesnt really need more than a few mL like 25-50mL max at this stage. if you give it more it's usually fine but it can lead to problems like what you have now. So basically the moisture is a breeding ground for "water mold" and this you need to fix by a longer dry period. usually the mold will disappear by itself and the plant will recover, but if it doesnt what you need to do is fix the root zone. This you can do by using additives like beneficial bacteria which take a while to fix things or humic and fluvic acid which will break down the problem roots and regulate the medium quite well. Hope this helps ! ๐