Backyard Aquaponics
A place to discuss aquaponics

I'm working on a small AP system that I can move around and take to demos and sustainability fairs, etc. Right now, the siphon won't start, or will output as much as the pump is inputting.

I know I have a vacuum in the siphon pipe, because I can lift if up and not lose the water inside. In fact, lifting it up a few inches often initiates the siphon.

This is the whole setup:



Siphon pipe:

I recently increased the size of the crenulations based on Thorn's paragraphs above, and that helped a fair bit.

Standpipe:

I've been making this various heights, and decreasing the size by putting an adapter on top. None of that helps.

Outlet:

From the side, for some more detail:

I've varied the angle of the last Ell from horizontal to vertical, and everywhere in between, in order to mess with the air trap. If I move it while the water in the growbed is high, the siphon will start. But in the next cycle, again the siphon will just trickle over.

I've also made the vertical section of the outlet pipe much shorter.
I've also removed all of the Ells beyond the vertical section of the outlet pipe.

I've tried many different heights for the air break tube, and have plugged it so it's not active, all again to no avail.

Which of these many variables is outwitting me? Anyone have any ideas?

Gar, and then I went and called my drainpipe the outlet. *sigh*

That setup looks awfully big, I think maybe you don't have enough water flowing in.
So the siphon half starts.
Then you lift the bell, raising the water a bit and increasing flow dramatically.
Some of your pictures wont display, so it's hard going trying to guess.
What are your pipe diameters?
Inflow, standpipe, bell, drain etc

I'd also like to see the pipe below the siphon, probably in the pics that wont display

The pics look good from what I can see in them. be sure your air break tube is slightly higher than your crenelations. Having an air break tube makes the air break easier because the tube usually has the hole at a horizontal plane so it's easier to break water tension. Is the size of your standpipe the same or slightly larger than the size of the pipe bringing in water? I find that is a good place to start.

Now that bacteria has built up on my standpipe, it breaks the water tension easier and begins with drops of water out. The drop rate increases until the siphon fully engages within a minute. If it takes more than two minutes it probably won't start. This is probably where others say that a bend at the bottom of the standpipe helps.

It could help others diagnose your issue if you post the internal diameters of your standpipe and siphon pipe. Also be sure any protective shroud has enough slits/holes to allow as much water through as your siphon can suck. If you have been testing this in an empty container, try it with the container filled as that will speed the process up (filling and draining) by more than half, that could help just by itself.