I love your system. I just set up something similar for rooting, its smaller but similar in concept.
I think that you will find that the fog will condensate in the secondary tub, forming puddles in the bottom. I hope that installing a gravity fed drain line for the excess water should be sufficient to remove it from the system.
You can then put it back in the solution if you like. But I will be letting it go to the toliet. Keep it fresh I say.
What say you?