Prototype works!     

 The 160gph aquarium pump set at lowest setting is filling the grow tub every 20 minutes.  

Bell siphon is working consistently.   Takes about 30 sec to start after water level reaches top of stand pipe. 

Also added the aquarium bubbler.  

Works much better with the longer vertical before the bend. 

45 degree elbows seem to work as well as 90 degrees.  

Hard to get a good picture of these things. 

Leaving about 1" of water before siphon breaks. 

Thanks again to Meg Stout for the Bell Siphon parts list I found at:                       http://3x5aquaponics.blogspot.com/2011/12/bell-siphon-parts-list.html