Thu check out posts #96, 97 and #101. I think that may work for you (don't forget the stop valve to control air pump power flow.)
Weedhound Reviewed by Weedhound on . GH WATERFARM USERS: SIMPLE RECIRCULATING SYSTEM Ok so I was at my hydro store yesterday and the BRAIN pulls out this kit from GH that makes your w/f set recirculating!! Ordinarily this isn't very exciting news EXCEPT...... Get ready.......:jointsmile: It uses an air pump and drip ring set up to move the water through the system. You do NOT NEED A WATER PUMP! Let me repeat that part: YOU DO NOT NEED A WATER PUMP. IT RUNS OFF A BASIC AIR PUMP. Rating: 5