Feedback on ebb and flow

A question from a fellow grower:

I was thinking about a system and would love to have your feedback on it :
Basically, it would be a simple ebb&flow system : the main tank empties itself periodically to flood the roots. What i would like to change is to replace the water pump by an air pump, that, instead, pushes air into the main tank as to force water to go flood the roots. The advantage would be that when the main tank is empty, the air pump will still be running, an therefore turning each pot into a DWC bubbling system.
What do you think ? How long do you thing a cycle should take ?

2-8 weeks veg , and 2- 8 weeks flower for regular feminished plant .