I was starting to notice a problem with some of the leaves on my black beans. They were getting a bit yellow but still had green veins. This, of course, can be a few things. I had recently fertilized the plants, so I did not think that was the problem. I started to think it was actually the closeness of the plants to the grow light. A little bit of research revealed this was probably my issue. I raised the light, and it seems to have worked!