Bell Siphon

thingiverse

To start with I modified the strainer section from a design by  (NorCalRobotics) with changes to vent and base; strainer not really needed as cutouts or drilled holes in pipe would work as well. The strainer does look cool! Added a large ring to make it clear my stand tube bulkhead fitting. The design is built around 2" pvc sc40 pipe. I also used a coupler on mine so I could easily change the length; could use one length of 2" pipe. The spillway fits on top of a 3/4" stand pipe controlling the upper water level. The center hole in the spillway is a vent to remove air that sometimes gets trapped in the stand pipe. I used a 5" piece of 5mm carbon fiber tubing pushed through the center hole protruding about 1" above the spillway. This pipe smooths the flow and vents trapped air. As the bell siphon works on both pressure and vacuum; any section exposed to air must be sealed. The vent tube is thin walled 3/8" tubing from Home Depot. Seams can be glued; I use silicone sealer as parts can be removed if need be.