Backyard Aquaponics
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I will get a better pic when my camera battery charges. Basically i have 25mm bulk heads about 3cm from the bottom of my half blue barrels. They have a media guard attached and the 25mm connected on the outside. Yesterday after removing the media from 1 barrel the siphon worked fine. I retested the barrel today it had the same problem without the media.

The problem is that the siphon starts when it reaches the loop point. But it is only a tickle and after 1-2 mins it stop (looks like it stops just under the loop if that).

Can anyone help me out here?

I'm not completely sure what's going on but I will take a stab-

Are the bulkheads protected from the gravel? (I assume the media guard is a slotted drain fitting) One theory I have is the bulkheads get clogged with gravel, the flow is restricted, and air comes up the drain hose to break the siphon. You may try a standpipe over the bulkhead so the water can flow quickly. However, the fact that you mentioned it can happen without media kinda throws this theory out.

Is the cut IBC a sump? It kinda looks like it is even with the growbeds.. you may try elevating the growbeds so they are a bit higher than the sump. Make the drain tubes longer, this may help. An experiment I would try is to fill the barrel, then put your finger over the end of the drain tube, then fill the barrel some more. Let your finger open a little, letting water out but not air in. If this allows you to drain the entire barrel, maybe putting a barbed fitting over the end of the drain tube will keep air from getting up in there when the water is draining, or you can make a U shape with the drain tube, it goes down and then up a little bit (water will stay in the U and keep air from getting up into the loop part from the draining end). Also if the end can be submerged in water that will work too.

What I think is happening is the siphon action is never really created... The top of the loop is full of air, and the water drains down in half of the tube while there is a constant channel of air to the outside in the other half of the tube. I don't know this for sure without really looking at it but the experiment above should help diagnosis.

Hi Concealed, thanks for the reply mate. I will try your test tonight. I suspect that it is the air as well.



Here is a pic of the sump and GB. As you can see the sipons should work I have done another test on the GB full of gravel. I just took out the 25mm tube all together and water came out at full speed so i think the media guard is fine (the gravel not clogging it up).

So now i just suspect the siphon itself.

i found that a bit extra height for the grow beds above the end of the pipe worked wondders for consistancy ie lift the blue barrels or lower the IBC so that the loop siphon finishes well below the bottom of the barrel. It worked for me anyway.

Hi Zman,
when you tried with a gravel filled GB, was the level of gravel Above the level of the outlet?
in the photo the tubs are only 1/2 full of gravel.
The water level will rise much faster when it is coming up through media than when it has to fill the entire surface area of the GB.
This faster rate of fill may just give you the extra bit of water pressure needed to kick off the syphon.

Also, As Concealed touched on, try putting a rightangle barb fitting in the bottom of the drain tube facing upwards,
this will give you a small airlock and help with starting the syphon.

.

I have tried all these but none seem to work

I made one exactly like this (minus the fitting and tube at the end)

Zman:
It was because you removed the Fitting and Tube at the end that they stopped working!!
The outlet of the siphon tube (regardless of top, bottom or side fitting) determines the depth at which the siphon stops!

In your case, it will stop at the level of the "elevated" outlet end of the siphon tube. By extending the siphon tube below the base of the water tank, you will empty it before any air enters the system.
Like this:

The siphon outlet must be below the lowest level you wish to achieve, the more the better!Cheers IanK

Hi Ian thought you hit gold there.

I ran outside and tried it 2 times. Unfortunately i must me the stupidest guy on BYA as i still couldnt get it to work.

When i had the plumbing in place as your suggested there was a little bit of a siphon action but stopped at the top of the loop again.

I kicked out the elbow just to see the lovely siphon action

Drop the top of your loop down significantly Hui....

Once you've got the siphon action working... add the media... then adjust the loop height to where it needs to be.... then adjust the flow...

Siphons take time and effort to get right, matching it to your flow and pipe sizes/drops etc.

Well, I'm in the same predicament as Zman. I can't get my loop siphons to work proper either. I really like Steves setup in the SS Barrels thread, but they don't want to work for me.
Here are pics of the first (and only) loop siphons I have set up. I stated before that the siphon worked, and it did, the first time. Every other time I filled the GB with just straight water, (no gravel filter pipe yet), and the blasted things won't work.

Not going to make any more until I get these figured out.

The siphon pipes are 1" Sealtite conduit that electricians use in wet locations. Got about a hundred feet of the stuff, so I figured, what the heck.
Loops are about 24" in length, MFT to barbed elbow in the end of the GB as depicted in the pictures. Drilled a hole in the 3" pipe to drain and made a V cut in the part of the loop that is shoved into the hole to assist with the flow. The exit end of the loop pipe is lower than the bottom of the GB.
The water fills to the top of the siphon, starts to drain fast, then slows to a trickle and the rest of the water sets in the GB.

Thought the issue was air leaking around the fittings, so I glued the pipe to the barbed end and put an "O" ring and locknut on the MFT part that is inside the GB.
Then I adjusted the top of the siphon pipe down, then up, then down again. If you look close you can see all the screw holes from my adjustments!

Bummer. Thought I had a good thing going on the loop siphons. Any help?

Does the bed then continue to flood... and then reactivate the siphon Bill...

If so... then it's probably working fine.... and any water remaining in the bed between cycles is inconsequential...

Maybe try to have the loop fall further down before going into the return pipe.

Actually... a very good point point Zman.... the outlet should indeed be about 1"/25mm below the bottom of the barrel...

Drop your return pipe down... and the outlet of the loop accordingly...