Backyard Aquaponics
A place to discuss aquaponics

Hex, surely not. siphons in my experience have a maximum flow rate. this flow rate is easily matched or exceeded by a pump.
I used to think what you are saying is correct. But unless there's something about this design that I still don't get, I'd have to disagree.

Hang on, I'm looking at the diagram again...
if it was all running happily and primed, and the inflow pump was stopped; at what level would the water in the standpipe settle?
I'm starting to think that the standpipe in the FT would drain almost to the bend (where the line is) and then any increase in water from the FT would have an empty pipe to fall into.

If so, then yes I like your design heaps more. Same principle as Janet, with only 1 extra bit added, but that extra bit gives you 2 feet of fall in your siphon, so the flow rate would be incredibly high...

Does what I'm saying sound right? Perhaps I need to build one and experiment :-)

Yep, the standpipe is always partially empty.. the height of the outlet tee piece effectively sets the static water level in that pipe.

I don`t know if the long drop of the standpipe in the tank and the added drop of the 2nd loop really make much difference but i`d say a syphon with a big drop would be somehow better than a short drop.

You can make a "Heath Robinson" test version with some clear pvc hose fixed to a board, using a barbed tee piece for the outlet tee.

I`ve made these before and they do work, so at least you know your effort won`t be wasted

longer drops are of course better. Water equations are identical to electricity equations. In this comparison, voltage or potential is the measure of the change in height of the water. so the lower your siphon pipe outlet, the higher the voltage... resistance = resistance, and flow = current.
so height difference =resistance * flow. so if height is increased, and resistance/friction is kept low, then flow must increase.