So I mucked around with s Bell siphon, using a 1” PVC outflow through a bulkhead in the bottom of a 35gal tote, a 1.25” adaptor for wider entry and a 2” and a 3” cap... no luck.
Frustrated, I switched to 1” pipes in an inverted U, but it wouldn’t reliably start. The open end of the tube was just off the bottom of the tote, the height is 6”
Finally, threaded 1/2” tubing through the 1” pipe extending a few inches down the drain. The GB end of the tubing has a fish filter tip.
Perfect. My 290 gpm pump with max lift 5.9 feet is lifting from a sump 3 ft below the grow bed entry bulkhead through 1/2” tubing. A simple valve controls flow, and I’ve been unable to find a setting that doesn’t result in a flooded tank (high flow 3mins, low flow 6 mins) that doesn’t create siphon reliably within a couple minutes of first drain.
I need to restrict the flow of the pump, however, in order to ensure that the siphon doesn’t “reset” endlessly after draining the GB. At the end of a cycle the siphon “breathes” 4-10 Times, and then loses siphon.
I think the smooth arc of the tubing makes the trapping of air easier to flush, but was pleased it was so easy to construct with slip fitting pvc, no cement. Easy to modify/improve/tinker.