Soil pH Levels
Any pH level between 6 and 7 is fine but you should aim for as close to 6.5 as possible.
This is from Green Man. It is my Bible.
I grow organic soil mix and don't worry about ph level ever.
Thanks for the better pictures. It looks to me like a water problem.
Only water once every two days around the time when the lights come on.
To discover when to water, feel the soil with your finger. if you feel moisture in the soil, you can wait a day or two to water. The soil near the top of the pot is always drier than the soil further down. You can drown your plant just as easily as you can let it get too dry and it is more likely to survive a dry spell than it is to survive a torrential flood. Water the plants well when you water and don't water them at all when they don't need it.
Good Luck!