As seen in one of my pics on week 16, you can see ...

The first suspect when you have weird leaf symptons is pH, specially if you are using tap water. That been said, you have several burnt tips on quite a few leaves. You mentioned you top dresed the soil, perhaps whatever you used was too strong, because it does look like a slight nute burn. Before doing anything I would meassure your water pH, if it's too high, that's the more likely culprit, if not then flush the soil with pH'ed water.