The idea of adding moisture during the drained cycle sort of defeats the purpose (air exposure) so I would wager it may lead to pythium if your not careful.
Dunno why you need fog.
Floom your reservoir with a powerhead perhaps? Would probably need to have it cut off during flood (relay inversing logic of lower float switch / denying power when not in drain cycle & when in drain cycle but not fully drained).
The DO isn't a big issue imo since...
The high switch is a nc contact and when it rises it opens stopping feed pump.
The low switch is a no contact and when it lowers it opens and the return pump is cut off.
Timer with dpdt contact relay would energize relay coil to switch power to the feed pump circuit for 15 minutes on (ebb) &...
I like dabs best. I have a bad back and i kicked the pain pills. Growing my own gives me 100% quality control on my meds. Now I can do dabs to relieve back pain so I can function. :)