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I have my barrelponics system running (sortof) and am having trouble with the siphon inconsistently stopping, sometimes it shuts off and allows the bed to refill sometimes it doesn't.

I loosely followed the university of Hawaii research in constructing my siphon, I used 1'' stand (drain) pipe, a 2'' bell and 7/16'' OD vinyl tubing for the snorkel.  The drain pipe had to be bushed down to 1/2'' for a section after the 90 and then bushed back up to 1'' for the second 90 that drains the water into the fish tank. This got the siphon working just fine.

The first attempt I drilled perpendicular to the cap straight in for my snorkel hole.  The siphon worked and shut off at first but then I noticed the snorkel became kinked and would no longer stop the siphon.  The gravel guard I have been using is 4'' OD but was not allowing enough space to prevent the tubing from becoming kinked.

I removed the tubing and drilled out the existing hole at an upward angle towards the bell cap so that the tube would naturally point downward, and this solved the problem of space between the gravel guard and bell.  I also used a larger diameter snorkel to try and increase the air flow into the siphon.  I tried this and the siphon STILL would not shut off.

I've adjusted the incoming flow rate to the beds a slight amount and this was working until a few minutes ago and the siphon would not shut off.  I reset it and now it is working again for the moment.

So what is the problem?  Is it just fine tuning the flow rate? Does the snorkel tube angle matter? (The gulp of air that the snorkel gets is part water part air.)  What about the drain, are there any adjustments I could make with 90's or other piping to help the siphon shut off?

I've pretty much done everything possible wrong at this point and am so close, any suggestions would be greatly appreciated

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The breather tubes are usually added to a siphon after a restriction is added at the bottom in order to help the siphon break because after a restriction is added at the bottom to help the siphon start it is then harder to get it to break properly.

Unfortunately many people just see instructions or pictures and do what other people have done but without knowing the reasons or purposes.

 

I tried to cut down the size of the 1/2'' restriction but only had limited success.  I am going to go back to 1" pipe and try and get the siphon to start that way, but I also thinking of changing the restriction to a 3/4'' pipe.  Any thoughts on this?  I don't think I can fit an affnan mod inside my bell with its current diameter unless I can find a 1" to 1 1/2" bushing.

I would not do the restriction on the bottom.  If you must slow the water at the bottom just do it with some 1" elbows to make a little trap.

 

And to do an affnan mod, you don't want a bushing, you want an adapter that will give you a sort of funnel shape on the inside.  Might take some searching around but you should be able to find something like that going from 1 1/2" to 1".

Hi All,

We call it an external reducer here.The smaller diameter fits around the outside of the existing pipe, this way the bore is never reduced.

I got rid of the 1/2'' piping and ran a horizontal line with a 90 - elbow - 90 and it's working.  Now to get the line to the other half barrel turned on, I'm guessing I'll need to make some flow adjustments, but it seems things are falling into place.  Thanks so much for all the advice!
Well, it works if I have the exact flow rate, otherwise the siphon won't start.  It is cycling every 4 minutes or so which seems a bit fast.  I just know I am going to have a headache when I try and get the flow rates dialed with the second bed running.  As far as finding a tapered 1" x 1 1/2" or 1 1/4" it's looking like I will be paying 4x in shipping the cost of the damn fittings.  Any ideas on more reasonable PVC sourcing or other options?

I had a problem as TCLynx stated with using a bushing and a coupling for the Affnan mod, I found a 1-1/2x 1 reducer coupling at work(blazemaster fire protection cpvc, not sure if it's foodsafe, but I was just experimenting.) and everything worked fine but the extra height of the fitting made my water level too high. Not wanting to disassemble the GB to cut the pipe shorter (in hindsite I won't glue the next one) I thought about how to make it work. Having recently seen that Affnan was experimenting with a smaller 1-1/4 x 1 reducer I decided to try a straight 1" coupling thinking that coupling would be a 1/4" larger than the stand pipe ID and should give me at least a little of the extra flow that makes the Affnan work. To my suprise it worked and hasn't let me down in three weeks. Worth a shot. Or you might try a plumbing supply house, they may have the correct fitting.

Josh Metten said:

Well, it works if I have the exact flow rate, otherwise the siphon won't start.  It is cycling every 4 minutes or so which seems a bit fast.  I just know I am going to have a headache when I try and get the flow rates dialed with the second bed running.  As far as finding a tapered 1" x 1 1/2" or 1 1/4" it's looking like I will be paying 4x in shipping the cost of the damn fittings.  Any ideas on more reasonable PVC sourcing or other options?
Josh if your siphon is not starting turn your 90 up a few degrees on the drain side, keep doing that until it starts. Josh a 4 min cycle time is way to fast. Do you mean it drains in 4 min. Cycle time is usually the fill and drain time combined. 20 min give or take a few is a good time for the cycle. I would slow the fill down till it takes about 12 to 16 min to fill. Then I would adjust my drain side to kick on once full by turning the 90 up to help start a slow fill or straight down if the siphon can start easily. Josh if you are running horizontal for a distance that leg in the drain must have fall as well to help speed up the water and create a draw or suction.
Josh just had a thought to help with the inlet side. Take 1 inch coupling and put about a 6 inch piece of 1 inch in the other side. Turn on your gas stove and heat the other side of the coupling  slowly turning it and not burning it. It will get soft and pliable. take a gloved hand and bend the coupling out in a wide funnel shape slowly. When you get the shape you want put under cold water to save the shape. PVC is very pliable when heated. We do this in pool construction and shaping electrical lines.

Hi David,

My first siphon i made an external reducer in this same way using a collar. I put some foil around the collar, stuck a pipe in one end, and heated the free end, then i put a tapered steel punch in the heated free end and wound it around to increase the diameter, and presto! I did this because i couldn't find the finished product at the nearby hardware store and it worked.

David Waite said:

Josh just had a thought to help with the inlet side. Take 1 inch coupling and put about a 6 inch piece of 1 inch in the other side. Turn on your gas stove and heat the other side of the coupling  slowly turning it and not burning it. It will get soft and pliable. take a gloved hand and bend the coupling out in a wide funnel shape slowly. When you get the shape you want put under cold water to save the shape. PVC is very pliable when heated. We do this in pool construction and shaping electrical lines.
Great Idea Harold on using something larger to create a funnel shape. Glad I thought of it haha.

Harold Sukhbir said:

Hi David,

My first siphon i made an external reducer in this same way using a collar. I put some foil around the collar, stuck a pipe in one end, and heated the free end, then i put a tapered steel punch in the heated free end and wound it around to increase the diameter, and presto! I did this because i couldn't find the finished product at the nearby hardware store and it worked.

David Waite said:

Josh just had a thought to help with the inlet side. Take 1 inch coupling and put about a 6 inch piece of 1 inch in the other side. Turn on your gas stove and heat the other side of the coupling  slowly turning it and not burning it. It will get soft and pliable. take a gloved hand and bend the coupling out in a wide funnel shape slowly. When you get the shape you want put under cold water to save the shape. PVC is very pliable when heated. We do this in pool construction and shaping electrical lines.
Master!   

David Waite said:
Great Idea Harold on using something larger to create a funnel shape. Glad I thought of it haha.

Harold Sukhbir said:

Hi David,

My first siphon i made an external reducer in this same way using a collar. I put some foil around the collar, stuck a pipe in one end, and heated the free end, then i put a tapered steel punch in the heated free end and wound it around to increase the diameter, and presto! I did this because i couldn't find the finished product at the nearby hardware store and it worked.

David Waite said:

Josh just had a thought to help with the inlet side. Take 1 inch coupling and put about a 6 inch piece of 1 inch in the other side. Turn on your gas stove and heat the other side of the coupling  slowly turning it and not burning it. It will get soft and pliable. take a gloved hand and bend the coupling out in a wide funnel shape slowly. When you get the shape you want put under cold water to save the shape. PVC is very pliable when heated. We do this in pool construction and shaping electrical lines.

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