Those are looking nice and healthy. When you add nutrients to your watering schedules there are a few ways you can do it. Your nutes probably have directions for recirculating systems. For my dirt plants, I do half that amount about every other watering, or exactly that amount every 4th watering. Seems to work out pretty well. Of course it is best if you under do it whenever trying something new. They won't die and they won't fry that way. You can always add a little more next time.

And yes, I never throw away those plastic CD tops. Another thing I use them for is humidity domes for individual youngsters. I usually buy the 50 or 100 pack, so the domes are 6" tall or something.

I hope that's not green light I see in the 3rd picture in the first set. Probably not.

I also hope Cabbage doesn't mind you borrowing his/her thread a little. Probably not.