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Bell Siphon Woes! After adding GB Media
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Author:  eddytheflow [ Oct 24th, '09, 11:48 ]
Post subject:  Bell Siphon Woes! After adding GB Media
Hey guys, having some bell siphon anger..!
Heh sorry this ended up being a long post, scroll down to bold font if you want to get straight to the point/symptoms.

Here's what I've got with my barrelponic system, setup CHIFT PIST, continuous flow, barrels cut long-ways:

1" (25mm) standpipe, 2" (50mm) siphon tube, 4" (100mm) gravel filter.
Using a 350gph (1325lph) pump, about 3 feet of head brings that down to 335gph (1270lph).
--divide that by two barrels and I've got about 167gph (632lph) going into each barrel.

The bell siphons did -not- work perfectly the first time, would not start worth a damn.
Remedy: adding U-traps underneath each barrel.
And voila! Both worked well enough (started and, with the addition of an air-break tube, stopped)

I began having problems with one after I filled one GB with red lava rock (what a pain in the ass to clean, BTW!),
The symptoms seemed to point towards not enough air being sucked in, an insufficient air break,
so I fooled around with my air break tube, raising it higher and higher to no avail.
I tried twisting around into a "U" shape so it would have more air, tried using a "T" adapter with a tube on one end, even tried pricking a pin-hole (ultimately several, in desperation) at the top of the tube...

What else did I try? I tried swapping all of the hardware from the siphon that worked to the one that didn't..
It still didn't work!!
At this point I should have realized that the only difference was the gravel... but I wasted a few more hours fooling around with the tube.

Finally began putting more gravel in the "working" GB and guess what?
It stopped working also..


Rather, I should clarify that they both work perfectly when I first set the siphons on top of the standpipes (the vacuum is broken no doubt).
The water level rises to about 1" below the top of the medium, then drains quickly to about 1" above the surface of the barrel.
The water then fills... and as it slowly fills I notice a trickle coming from the drain into the sump, it slowly increases to a steady, slow pour, and by the time the water level is only about 1/3rd of what it should be draining at, the siphon starts back up again.

It sounds like an air-break issue, but I've sallied around with it for hours and hours, nothing related to air-breaking seems to help.

What on earth did adding GB Media do to my siphons?

Thanks anyone for helping me through this. Let me know if pictures are going to help (i'm thinking of KudaP for some reason..)
And I have a feeling TC might just tell me to give up on the barrels with bell-siphons...

Fie!
Author:  novaris [ Oct 24th, '09, 12:24 ]
Post subject:  Re: Bell Siphon Woes! After adding GB Media
Im not sure that I am right but I have had similar problem with mine, I think it has to do with the rate of flow into the siphon from the outer stone guard, the combination of rock and holes into the chamber slows the water as the siphon drains it starts to break but the water level suddenly rises as the siphon stops and water continues to flow into the chamber. This seems to form a vacuum in the top of the siphon and hold the water. As the water level rises pressure eaqualizes the vacuum and the siphon starts again. To test it try lifting the bell cover if you feel weight then you have this problem. In my case I get around because I have serial grow beds and put a drain hole in the standpipe this allows the excess water to drain and eventually break the stand pipe. I think TCLynx has suggested a method of outlet to break the seal but I have not tried it.
Author:  Simo [ Oct 24th, '09, 12:57 ]
Post subject:  Re: Bell Siphon Woes! After adding GB Media
+ 1

I had the same problem and tried all the things you have mentioned and agree with Novaris, but mine was because my rock guard had too few holes and only one siphon for 1000L of GB. Water was siphoning faster than the rock guard was letting water drain to the base of the siphon there for a stop/start action and incomplete siphon break.

If you plan on sticking with bells maybe more holes on rock guard, I found this paper very helpful in regrads to bell siphons:

http://www.soils.wisc.edu/sswmp/pubs/9.12.pdf

I gave up on Bell siphons when I found a better, easier and more reliable siphon call "The Affnan", google "Affnan" and "Bell siphon" he has a few vids on You tube which can help.

Basically it is a bell with a funnel in the top, as water overflows funnel fast enough a whirlpool sucks all the air out of the top of the bell and siphon starts, air entering crenulation stops siphoning. No air break tube, no water trap.

Attachment:
SDC10436.JPG
SDC10436.JPG [ 190.3 KiB | Viewed 6917 times ]

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.

Attachment:
SDC10440.JPG
SDC10440.JPG [ 192.41 KiB | Viewed 6921 times ]

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.

Attachment:
SDC10442.JPG
SDC10442.JPG [ 171.41 KiB | Viewed 6911 times ]

Assembled unit looking very neat.

Trust me these will save you a lot of time and trouble, worked for me any way.

I am thinking about starting the "Affnan Fan Club" :wink:
Author:  eddytheflow [ Oct 24th, '09, 15:11 ]
Post subject:  Re: Bell Siphon Woes! After adding GB Media
Thanks Simo and Nova,

Simo, I've run across your posts several times about the affnan siphon and, to be honest, it seemed a little sketchy just because nobody seems to use/have used them!
But at this point, and especially because our symptoms seem to match up, I think I'm gonna give it a shot.

Nova, I just tried drilling a 3/8" drainhole in my standpipe, near the bottom, and little or no difference :(
Even tried flipping it upside-down for fun, and putting another 3/8" hole in it... doesn't change a thing, except I have an even bigger residual drip.
I'd be interested to see what TCLynx's suggestion was--I haven't run across it yet.

It seems like an easy enough thing to do, Affnan's siphon. I just need to go out and buy a reducer and a joiner and replace my original standpipe with it.
I might even -have- to remove my U-trap... and shux, i was just starting to like it.. :?

for some reason I don't think my particular issue has to do with the holes in my gravel filter:
while I was messing around with the siphon I heaped the gravel around the edges of the bed, removed the filter altogether--same results despite a filter.

thanks for the info and i'll keep the info coming if you keep throwing out ideas!

I'm sure I'll be out of them if Affnan falls through
Author:  Simo [ Oct 24th, '09, 15:56 ]
Post subject:  Re: Bell Siphon Woes! After adding GB Media
I hope the Affnans work for you as well as they do for me, I know how frustrating the airlock/dribble problem with the bell siphons are :cussing:

Make sure you remove the U-traps, in my way of thinking this is critical, good luck :thumbright:
Author:  Taz [ Oct 24th, '09, 16:14 ]
Post subject:  Re: Bell Siphon Woes! After adding GB Media
Simo wrote:
No air break tube, no water trap.
:cheers: Thanks Simo, I've seen Affnan's vid about his siphon and I was wondering if he used a U-bend air trap.
I know a few people have had trouble with the size of their air traps trying to get them stop and start effectively.
Author:  TCLynx [ Oct 24th, '09, 22:06 ]
Post subject:  Re: Bell Siphon Woes! After adding GB Media
Bell siphons. Keep in mind, I've only kept one working long term. I've had more luck with loops myself.

The size of the siphon has to be balanced with the inflow to the bed. I kinda think that perhaps your siphons are a bit big but you say you got them to work at first with no media so maybe they are ok.

Keep in mind that the extra elbows and such on the bottom of a Bell siphon drain are an add on to solve a problem, they are not necessarily needed for the bell siphon to work. Also the breather tube is another add on that is not necessarily needed unless it is to solve a problem.

First, what was the original problem.

Did the basic siphon just trickle over without fully starting? If that is the case, then you either need a faster inflow or to add the u-bend trap in the bottom.

Or did the siphon start just fine but then not completely cut out? If that is the case then what you needed was the breather tube, not the u-bend trap.

Since you are having trouble with getting the siphon to stop properly, try simply removing the u-bend trap parts from below the siphon drain. The u-bend trap is probably stopping the siphon from getting a good gulp of air from the bottom and therefore the vacuume and siphon is staying intact even after the siphon should have stopped.

And tell us what happens without them.

This is where the really challenging part of getting siphons working with longways cut barrels comes in. See the barrels cross section changing with depth is going to make it appear to the siphon that the barrel fills very quickly near the bottom and very slowly near the top. So how do you get the siphon to kick in properly at the top of the flood and yet stop properly at the nearly empty state.

As I've said before, I know it can be done because some people have managed to do it. However, it is often accomplished using an intermittent flood like in the barrel ponics system with a flush tank or pump on timer. All my half barrels cut the long ways are either part of a barrel ponics system or getting their inflow intermittently in some way.

Perhaps try some of the other ideas people have given as I'm no expert on bell siphons.
Author:  eddytheflow [ Oct 24th, '09, 23:58 ]
Post subject:  Re: Bell Siphon Woes! After adding GB Media
Quote:
Did the basic siphon just trickle over without fully starting? If that is the case, then you either need a faster inflow or to add the u-bend trap in the bottom.


Yep, got the slow trickle without any start. I put the U-trap in and it started, -then- it wouldn't stop

Quote:
Or did the siphon start just fine but then not completely cut out? If that is the case then what you needed was the breather tube, not the u-bend trap.


So i added an air-break tube


But you make a good point... I guess I haven't tried removing the U-trap after putting the gravel in.
I'll see if that works before trying the affnan
Author:  eddytheflow [ Oct 25th, '09, 00:48 ]
Post subject:  Re: Bell Siphon Woes! After adding GB Media
Just removed the U-trap and put in a taller drainpipe.
What happens, I think, is the siphon fails to start.
It just seems to pour through without initiating the siphon, and as a result reaches an equilibrium with the water coming in/going out.
Ugh.
U-trap seems necessary, perhaps I'll go buy a few more elbows and make it a bit smaller.
That and Affnan stuff.
Author:  eddytheflow [ Oct 25th, '09, 00:55 ]
Post subject:  Re: Bell Siphon Woes! After adding GB Media
i should clarify.

Removing the U-trap required more water-flow to actually start the siphon.
When it's started, it actually drains slower, leading to that damn equilibrium state.

Interestingly enough, the U-trap allows for siphon starts at lower water inflow rates,
appears to actually allow the GB to drain noticeably faster.

and, of course, the downside is that breaking the vacuum becomes near impossible (in this case)
Author:  TCLynx [ Oct 25th, '09, 04:13 ]
Post subject:  Re: Bell Siphon Woes! After adding GB Media
Some people have done things like cut off part of the last elbow so that there is less water pressure to overcome in starting the siphon and therefore perhaps a slightly easier time sucking a gulp of air.

Or perhaps just a larger breather tube is needed to balance the u trap in the bottom.
Author:  Simo [ Oct 25th, '09, 06:21 ]
Post subject:  Re: Bell Siphon Woes! After adding GB Media
Affnan
Author:  eddytheflow [ Oct 25th, '09, 13:24 ]
Post subject:  Re: Bell Siphon Woes! After adding GB Media
my first attempt at constructing an affnan was pretty bad.

Lowes, for some reason, doesn't stock -any- reducer couplings.
They have a few bushings and threaded knick-knacks but nothing with that characteristic funnel shape (which seems essential).
I bought some parts that would fit inside of a 2" siphon--I don't even really know what I bought,
i guess it shouldn't be surprising that it didn't work.

Simo, did you buy your reducer coupling online or from a hardware store?

On a separate note.. if this ends up being hopeless I may have to invest in a timer and flood and drain.
And just to clarify, the pros and cons would be...:

f&d:
+not much worry of overflow,
+less parts to malfunction,
+simple
-need to invest in airstones (or additional airstones)
-less efficient transfer of nutrients.. ?

Is the only benefit of an autosiphon the aeration and the loss of need for a timer?

hmmmm
Author:  Simo [ Oct 25th, '09, 13:49 ]
Post subject:  Re: Bell Siphon Woes! After adding GB Media
All my PVC fittings are standard reticulation sizes bought from a small town hardware store. Try a retic or garden shop.
Author:  fishfodder [ Oct 25th, '09, 19:07 ]
Post subject:  Re: Bell Siphon Woes! After adding GB Media
My understanding is that creating a siphons requires that a section of pipe be completely full of water. That water moves (due to gravity) creating a vacuum behind it. That vacuum is filled by more water and the process will continue until such time as air is able to enter at either end. This is true whether you are using a simple loop siphon or a bell.

Looking at Afnans siphon, it looks like he is creating the syphon within the stepped standpipe i.e. the water comes in at the wider top section and is contricted down to completely fill the smaller space and the suction is created. Very clever.

Another way of doing it is to create the suction at the far end of the drain pipe (the air trap method). This can be done with a u-bend or, the method I used iis to have the drain pipe fall vertically down to ground level directly under the growbed then rise up slowly by about 95% of the pipe width.

The 95% rise means that the pipes slowly fill with water and only slightly more than 5% of the pipe total capacity is required to completely fill it and kick off the siphon. With this method air can enter under the bell and at the end of the drain once the flow slows down.

Breather tubes also help but I don't use them on two of my beds because I don't mind the fact that the siphon takes a little while to break, it lengthens the cycle a little.
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