The edges of the yellowed leaves looked sort of burned or something.....that doesn't really follow a nitrogen def imo. Unfortunately, I grow hydro so soil is not my strong point at all.

I'd be guessing one of two things really.......either the ph of your water is off or perhaps your soil. The other would be too much nutes in the soil for your young plants.

If you can buy some drops to check the ph of your water and soil runoff that would be great.....the drops are very inexpensive and worth knowing about your ph because that being off will mimic all sorts of other problems.......including nute burn. That would be the first thing I would check and if the ph of those are normal I'd go to nute burn next.