Bubbler/DWC type setup

I have some plants early in the veg stage. I have them in 2" netpots for now and will transfer them to 4" this weekend. I have them in a small tub with two bubblers at the bottom. The water level is about 1.5" to 2" below the bottom of the netpots. Is this the right water level setting?

Also, I have them under a 55watt 50/50 power compact light off my fish tank. The light is about 2" above the humidity dome. Do I periodically need to spray the plants to keep them moist, or am I fine?

Most of them have roots showing through the plug. A couple of them have roots that dangle about 2" down from the netpot.

As far as nutes, I used distilled water and some seaweed extract addative during cloning. Do I need to dump out the water and start with fresh distilled water when I add the GH nutes? I will be following the GH table on how much to add.