For what it's worth this is what I would do if you don't care about plant count. I would get a new seedling started asap. I would shove the sickly one in some corner of the tent and think of it as a "bonus" plant. Maybe that plant pulls through and what ever weed you score off of her is your "bonus". Not only some extra weed but extra experience that will be more valuable than anything. I've done this myself a few times before because I hate losing out on a seed. Keep it in a smaller pot if you can and don't let it get in the way of your big girls.
GL
GL
In my opinion logic dictates to cull that plant now. Every spot under my light has a "value" in grams/time of what that light on average will bring. If I plant isn't going to bring close to the same value as another one can in that spot, than it's best to cut your losses early. As I mentioned earlier, there is a cut off when the cost/benefit isn't worth culling your plant. If you can spot runts early, and I think @davisgirl is correct with her assertation, the OP will see a far greater value in culling the plant now in a timely matter.Go with logic and not feeling. Youll thank me later![]()