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having a problem with an Affnan siphon, help?
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Author:  Rachel [ Jul 24th, '10, 12:52 ]
Post subject:  having a problem with an Affnan siphon, help?
Still quite new to this so thanks in advance.
My siphon kicks in great, it drains the 100 gallon grow bed about 6 inches and then cuts off with about 8 inches of water left. The bell reducer is a 2 to 1.5" with a bushing immediately bringing it down to 1". (The siphon cuts off when the water level is about 2" below the bushing.) The 3" standpipe has one of those "temporary" caps glued in it, this way it still fits inside a 4" pipe that keeps the rocks out. It sits tightly in a bulkhead fitting. Anyone know why this is happening and how I can fix it?
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Author:  Decal [ Jul 24th, '10, 13:08 ]
Post subject:  Re: having a problem with an Affnan siphon, help?
I haven't made an Affnan type bell siphon, but I do you the type with the tube to break the suction.

I had a similar problem with mine, turned out to be air getting in at the top. Just make double sure that the top is sealed?

Also make sure your stand pipe is dead centre to the bell cover. I use 3 screws through the bell to make sure it all lined up.

I hope this helps.

If non of this helps can you please let me know what did? :)
Author:  fishfodder [ Jul 24th, '10, 16:02 ]
Post subject:  Re: having a problem with an Affnan siphon, help?
[quote="Rachel"]Still quite new to this so thanks in advance.
My siphon kicks in great, it drains the 100 gallon grow bed about 6 inches and then cuts off with about 8 inches of water left. The bell reducer is a 2 to 1.5" with a bushing immediately bringing it down to 1". (The siphon cuts off when the water level is about 2" below the bushing.) The 3" standpipe has one of those "temporary" caps glued in it, this way it still fits inside a 4" pipe that keeps the rocks out. It sits tightly in a bulkhead fitting. Anyone know why this is happening and how I can fix it?

Terminology first so we remove some confusion :)

Standpipe... that is the small pipe that you have your reducers on.

Bell Cover... that is the larger pipe with the yellow cap.

The standpipe needs to sit into your grow bed outlet. Your bulkhead fitting if that is what you are using to make the hole :)

You do not want your bell cover sitting tightly into anything. Your bell cover needs to sit freestanding on the bottom of the growbed to allow water to enter through the crenalations.

In the picture below the standpipe has a reducer on it but that reducer sits snugly into a sink waste fitting that is in the bottom of the grow beds. The bell then sit over the top of the standpipe with the crenalations sitting on the growbed floor, allowing the water to rise up inside the bell and then down the standpipe.

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Hope that helps.
Author:  Ian [ Jul 24th, '10, 18:11 ]
Post subject:  Re: having a problem with an Affnan siphon, help?
It could be that the entry for the air break tube is not air tight? It only takes a tiny air leak to stop the siphon, so stack the silicon around the break tube where it enters the Bell tube. Really, if you are going to use an air break tube it should be as close to the top of the "bell" as possible, just make sure everything is air tight, not just water tight. There is a difference.
Cheers IanK
Edit: :? sorry, looking at the wrong photo. Try removing the reducer at the top of the standpipe. It is not allowing enough flow around the gap to the Bell tube, as the Static head is reduced. It starts OK but then stops as the restriction can't supply the water to keep air from coming back up the standpipe. I had exactly the same problem with one of my siphons. Removed the restriction and everything was fine. IDK.
Author:  hewitttrev [ Jul 24th, '10, 19:45 ]
Post subject:  Re: having a problem with an Affnan siphon, help?
Rachel

I recently had the same problem.
in my case I had an air leak on the top of the bell housing which was
causing the siphon to cut out early.
I created a better seal on the top by using kitchen cling wrap held
on to the bell housing with a rubber band.

hope this helps

Trev
Author:  earthbound [ Jul 24th, '10, 21:12 ]
Post subject:  Re: having a problem with an Affnan siphon, help?
Yeah sounds like it may possibly be an air leak at a guess..

Nice use of toes... :)
Author:  Rachel [ Jul 25th, '10, 06:55 ]
Post subject:  Re: having a problem with an Affnan siphon, help?
Thanks all! I forgot to click the "notify me when there's a reply" thing, so I'm just now seeing all these posts--- after I fixed the problem by rubber-banding some cling film to the top of the bell cover. Got a laugh out of reading your post hewitttrev. :lol: I had made the rookie mistake of assuming if it was glued well, it would be airtight.

Thanks for the terminology corrections fishfodder. I don't have any aquarium silicon around, so I'll pick some up tomorrow and fix it sans cling film.

I really appreciate all the help, now I will hopefully be able to begin cycling the tank next week!
Author:  Decal [ Jul 25th, '10, 07:41 ]
Post subject:  Re: having a problem with an Affnan siphon, help?
Glad we could be of help!

Please post some pics of your system? Do you have a thread under members systems?
:flower:
Author:  Rachel [ Jul 26th, '10, 04:50 ]
Post subject:  Re: having a problem with an Affnan siphon, help?
I do!
It's here: viewtopic.php?f=18&t=7878&start=15&st=0&sk=t&sd=a
Author:  desertrat [ Jul 26th, '10, 10:11 ]
Post subject:  Re: having a problem with an Affnan siphon, help?
Hi Rachel
+1 Sounds like an air leak which I suspect would be level with the point that your siphon cuts out. Hope this helps if you haven't already solved the problem.
Author:  Rachel [ Jul 26th, '10, 12:01 ]
Post subject:  Re: having a problem with an Affnan siphon, help?
Yep, thanks desertrat, it was an air leak and I solved it temporarily with cling film and a rubberband, which apparently isn't a unique solution! The airleak was in the cap of the bell cover. It was small as a hair and it just took a few minutes to suck in enough air to break the siphon. For all future siphons I'll be sure and silicon the bell cover from the get go!
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