It's easy to check, just uncover the plant roots and look.When I was using hydroponics [deep well] and aeroponics [spray system] the aeroponics had much more hairy like roots which would use the nutrients much more efficiently. In the hydro system the roots were submerged all the time, and the aero system the roots were sprayed off and on. My current aquaponics system runs for 15 min. every hour which seems to be working great. So I would say that a little dry time is good as a finer set of roots should clean the water better.