the pump schedule should go as follows: 20-30 seconds pump on and 3-4 minutes pump off
all plants need time to dry out. dry encourages root growth. clones are no exception
i run my pumps with 30 seconds on, 3-4 minutes off
i posted my diy aero here:
http://www.rollitup.org/2278381-post40.html if you wanna look i get roots in about 3-5 days