Your clones are looking pretty rough. were these taken from healthy mothers?
800ppm is high for cloning. Why not just use plain tap water and wait until they root?
I never took a light reading for cloning but i typically have a fluorescent light around 2' above the clones. They don't need much light whatsoever.
If i'm cloning in rockwool, i make sure to soak and then shake out all the excess water as the cubes can retain quite a bit of water. You dont want them too wet.