I think you have several problem going on here. You will need to post all the details. What kind of water are you using, what kind of method are you using, what kind of ferts, what is ph an ppm levels?

The black splotches are likely 1 of 2 things. You mentioned misting water on the leaves, I would stop that. The water you might be using is leaving droplets on the leaves and depending on how low your lights are, may be burning the leaves and causing the splotches. The other likely culprit is that you are using RO water, distilled water or spring water. Your water is short on needed minerals mainly calcium and magnesium. There is a product called cal-mag that you need to use when using anything other then tap water. I mix my water 50/50 with RO and tap to give me a good mix.

The yellowing is likely due to insufficient nutrients. I have never heard of a leaf yellowing so that it can focus on root growth. Believe me, a plant can handle both root growth and leaf growth.

The crisping of leaves is likely due to insufficient watering. Again you should post every detail of your system and method so that we can identify where you are falling short.