Looking at your pictures again I'm not seeing any signs of excess water. I still think you have a pH issue with your soil.
Regarding the height of your light, while the plants are still in the vegetative state I would set your light at about 16" above the top of the plants and then raise or lower it to maintain 1" of space between your leaf sets, which are called nodes. Once they go into full flower, after about 6 weeks, you can lower it to 10-12" above the plant top.