Backyard Aquaponics
A place to discuss aquaponics

I finally went and got myself a decent pump today but now I have a problem of the siphon not breaking when it reaches the 6mm at the bottom of the standpipe because (I assume) the inflow is great enough to keep the pressure within the bell if that makes sense. I've considered two options:

A) drill a second 6mm hole in the bottom of the standpipe
B) install plastic tubing from the top of the bell to within an inch of the bottom of the GB

Any of you physics boffins able to point me in the right direction?

Cheers

Firstly - you dont need plastic tubing to break a siphon - ever, you have a water volume issue

Just remember this:

If the siphon will not start there is not enough water flow.....if it will not stop there is too much

If it will not break, you need to regulate it - tap etc

How about a spray bar to reduce the amount of water heading up to the GB and aerate the FT? Would it be as simple as a T just after the pump and sprinkler nozzles screwed into poly pipe (I am already using poly rather than flexible pipe)

Yep that would work, but a simple pvc ball valve on the return would regulate it.

What Mantis said

again - dont make it more difficult than what it is -

If the siphon will not start there is not enough water flow.....if it will not stop there is too much

I don't have an air pump though so a spray bar would compensate for this

So it turns out the spray nozzles don't reduce the pressure enough as well as suffering blockages in any case which would reduce their effectiveness so I am going to have to install a valve to reduce flow to the GB. I didn't want to put pressure on the pump so I have come up with the following design. The two advantages are that it will not put back pressure on the pump and that the excess flow will flow back into the FT and create further aeration.

How long is the tail on your siphon? Specifically what is the vertical fall from the bottom if the gb to where the flowing exciting the gbreaches atmosphere?

Many syphons fail to break because they don't have a big enough fall.

Wouldn't be more than an inch, basically just enough pipe to go into the elbow joint. This sounds about right too as it kinda gurgles like it's about to break and then fill back up again. Unfortunately the only option I've got of dropping it further is to put a hole in the side of the FP but that's no bigger I suppose and will be used when I eventually convert my system to CHIFTPIS

If your holes in the spray bar are getting blocked and not allowing enough water pressure through them, then the holes are too small... Drill them out with a larger bit...

What about the issue of the spray bar pumping solids back in the tank?

Not an issue for me coz I don't do it.....

they just get circulated like everything else. I wouldnt stress too much, its more important that the system actually functions.