Backyard Aquaponics
A place to discuss aquaponics

Greetings,

I hope I can get advice from the experts. I've been reading through al lthe posts and I thought I made an autosiphon correctly but it doesn't seem to want to work. The bell housing is 3 inch (76mm) wide and 13 inch (330mm) high. The drain pipe above the bottom of the tank is 2 inch (57mm) wide and 11 inch (280mm) high. The drain pipe extends below the bottom of the tank by 5 inches (130mm). There's a 3/8 inch (10mm) plastic tube from the top of the bell housing to the bottom.

The water just drains to the top of the drain tube and a suction/siphon doesn't seem to occur.

Any and all suggestions would be gratefully appreciated.

Thanks,
Greg

You will probably need to put a u pipe on it like the one I have

download/file.php?id=20780

this will increase the pressure....it takes to start the siphon

hope this helps

JT

The vertical gap between the top of the inner pipe and the top of the outer pipe looks kind of big to my eyes. Maybe make the inner pipe longer or the outer pipe shorter so that it is closer to the cap? It looks like everything is sealed up good so I don't think it is leaking vacuum. Also maybe the cuts at the bottom need to be bigger, if the flow is not enough through the bottom of the outer pipe that might keep it from starting.

Do you think the pump flow is big enough to keep up with this large of a siphon? The flow has to be big enough that the water level inside the pipe climbs to the point that the vacuum can establish. If the flow is not enough to do that then it will just keep trickling and not start.

I am not sure because I can't see inside one but I am pretty sure that when the siphon establishes that the entire cap is full of water and doesn't have air, that is why I'm wondering about the large gap to fill up there... HTH!

But first try a u-pipe because that's an easy fix.

That would be my guess too, it's a fairly large siphon, mine is a bit smaller and needs about 1500L per hour flow to trigger the siphon, and yes you should try the U or L shape end.

The sheer size of the siphon, and by that I mean diameter will cause you grief.
You need to have enough flow to fill the entire top of the bell before it has a chance to drain.
Try a u bend at the bottom, otherwise downsize the standpipe, the bell size is not so critical.
It is important that you provide SOME resistance to get a bell siphon to fill.

How big is your bed? What is the flow rate?

My bells are 2" and my standpipes 1" and I had trouble getting some to go.
Other (more successful) Aquaponicans use 3/4" stand pipe with a 1-1/2" bell I think. but definitely 3/4" standpipe... my next siphon I will make 3/4" and upsize if necessary, after all a bigger hole is easier to alter to than a smaller hole

Hey,

I had a simmilar situation, my drain pipe is 40mm and i couldn't get it started priming, and this is how i solved the issue(now it starts with ~300 l/h inflow)


Hope it helps, it looses the need for special elbows and more fittings. I just took the PE pipe and bent it, and i made the special fittings(reduction to 3/4 inch) to fit the drainage pipe which already has a built-in seal, it can be done even more simple.

Good day!


p.s.

The U-pipe did not help me here, i tried everything and only the reduction with elbows helped, because the pipe has to get clogged with water to start priming and with 40mm diameter you need at least 1000L/h if not more to start it priming.

has anyone used this type of syphon?

Affnan's Bell Valve

http://affnan-aquaponics.blogspot.com/2009/05/how-to-make-bell-valve.html

Seems like a good idea and can't see why it would not work.

No need for air hose to break suction/syphon action.

Quachy

search for bell siphon...

2 things from that video
1. Glueing down the screen is a bad idea, as we often give it a sharp rotate to sever any roots threatening to invade the plumbing.

2. the size adapter on the standpipe is an interesing idea. I don't know if it will work, but it seems to suggest easier starting of the siphon. I want to try this on my system at home.

I agree with the gluing thing, I prefer it not glued for the same reasons.

I am going to give the adapter idea a go his weekend on my problematic siphon (does not always break using the air pipe - just need to make the air hose wider in diameter but haven't got around to it yet.)

Will post results.

Quachy

I await eagerly, however my prediction is it will help with starting, not stopping... we shall see eh?

I don't know Kuda, looking at it (with my limited knowledge) once the water level gets down to the crenation at the bottom of the bell (where the water flows in to be drained by the standpipe), these should do the exact same thing as the air hose, just much much bigger in terms of air being sucked in to break the siphon.

I may be wrong but people please correct me if this is the case.

Quachy

Set 2 new grow beds up for my fingerling/isolation tanks (my current test set-up which will be my fingerling set-up when big one up and running) today with 15mm drain pipes. Water just trickling into growbeds, I have a 15-25mm adapter on top (instead of a 25-50mm as per Affnan's). My crenalations at the bottom of the bell is not as neat as Affnan's but hey, can't see these anyway. Anyway, they work a treat! Little gurgle gurgle and then stop! Had to go off and play golf (tough life when your on holidays) so couldn't take photos. Will do tomorrow and maybe a video as well. So, I can say that Affnan's bell valve works! Will let people know of any issues I have as i progress.

Quachy

Built two Affnan siphons today, very easy to do, worked perfectly straight away, I can't recommend them enough so much simpler and more reliable than freakin bell siphons with water traps and air break tubes. Pictures below.



All three parts prior to assembly. The bell is 50mm, the funnel shaped stand pipe is made from a 32mm to 25mm reducer with a 20mm joiner shoved in the 25mm end effectively creating a 32mm to 20mm reducer. Any similar ratio of internal pipe diameter reduction would have the same effect of creating a vortex once the water starts flowing down the funnel standpipe which sucks the air out of the top of the bell creating the siphon action. Siphon is broken by air entering the crenulations and the water in the bell is free to drain as there are no water traps.




Top down view of the funnel standpipe in the bell housing. I know the gap around stand pipe for water to flow is very small but trust me this siphon sucks just as hard as the traditional bell siphons I made and works even at low GB inflow rates.



Assembled unit looking very neat.

Hey there Simo!
Nice work and thank you for the contribution!

I was wondering is there an elbow under the stand pipe or does it lead straight into the bigger drain pipe beneath? BEcause i couldn't get the siphon working(starting and stopping properly) if there was no elbow or pipe reduction under the standpipe(under the GB).

Thank you!