Problem with my bell siphon

[Louise]

I've made a bell siphon after the instructions in this video:Plastic bottle bell siphon

When I tested it without substrate, pumping water from the bath tub, it worked well, and I managed to adjust the pump flow so that one ebb-and-flow cycle took about one hour. However, once I had it running on top of the fish tank, the pump flow didn't remain constant, maybe because of debris.

It keeps getting into a kind of equilibrium, where the siphon doesn't take in air and stop its emptying, just slows down to the same speed that the pump is adding water. The result is a constant low water level, and drought damage on some of the seedlings.

Do I need bigger gaps in the bottom of the bottle now that I have substrate in the box than when I was testing with only water?

I've also tested different downspout alternatives, because a while back I had the opposite problem - the water level stopped in equilibrium at the maximum level, with the siphon not getting the vacuum effect, just emptying at the same speed as the water was being pumped up. I tested having the downspout hose bent in an L-shape, or narrowed by another piece of hose inside, constricting the bottom.

Here are some photos of this test-system (lower down in the thread, first are some pictures of my not finished greenhouse system):

http://aquaponicscommunity.com/forum/topics/louises-first-aquaponic...

Based on this trouble with the bell siphon, I'm considering whether to have another method of emptying the bigger system I'm about to build. What system would you suggest? 

[David Hart]

If the siphon doesn't break....slow down the water comming in, by diverting some back to the fish tank....or...add a snorkel; tube.

Lots to know about siphons....do a search for 'Affnan'. He has lots of great info at his site.

Good luck

[Louise]

"If the siphon doesn't break" - do you mean that literally, as in the siphon breaking apart, or as in "starting to drain"?

Please explain snorkel; tube too. Im not quite familiar with the terms used here, and English is not my first language.

[Louise]

I found Affnan. This one seems good, if I can get hold of the right parts:

http://www.youtube.com/watch?v=kmxsI5ZRLA4&feature=player_embed...

[TCLynx]

If you reach equilibrium with the high water and just trickling out the siphon but not Starting the siphon, then your water inflow to the bed is too slow.

If you reach equilibrium with the bed almost drained but the siphon not being able to get a good gulp of air to STOP (break) the siphon then either

1-maybe your crenelations at the bottom of the bell are restricting the flow and they might need to be a touch bigger.

But more likely

2-your water inflow to the bed is too fast, do as Dave said, slow the water in flow tot he grow bed a little bit by bypassing some of the flow back to the fish tank, and then you will probably be all good.

(see now that you have media in the bed, there is less space for water in the bed and your pump is able to flood the bed faster so you need to adjust the flow rate a little bit.)   Then later if suddenly you find the bed is getting caught in the constantly flooded only trickling over but never really starting the siphon state, it will probably just mean you need to clean the pump since things will probably slime up and slow it down a bit over time.  Sometimes simply turning the pump off for a few minutes to let it backflush can take care of some of the problems.

[David Hart]

Louise, So sorry, I didn't realize you were from Sweden...."break' is one of those funny/odd words in English...as a noun, I found about 30 different meanings. As a verb (transitive and intransitive) I found almost 60 examples, with different meanings.

As TCLynx already pointed out, this time....'break' means to 'stop'....not to be confussed with applying the 'brakes' of a car to 'stop' :-)

 

This PDF shows 'snorkel  tubes'...

http://www.sip-hawaii.org/files/Aquaponics%20Handout%20-%20Siphon%2...

I don't think Affnan uses snorkel tubes (?) but I add them to my Affnan style bell siphons. Seems like I get a quicker stopping of the siphon.
Louise said:

"If the siphon doesn't break" - do you mean that literally, as in the siphon breaking apart, or as in "starting to drain"?

Please explain snorkel; tube too. Im not quite familiar with the terms used here, and English is not my first language.

[Bob Campbell]

keeps getting into a kind of equilibrium, where the siphon doesn't take in air and stop its emptying, just slows down to the same speed that the pump is adding water. The result is a constant low water level, and drought damage on some of the seedlings.

http://chicoaquaponic.blogspot.com/2012/03/bell-siphon-my-conclusio...

[Joshua flores]

From what i've seen and use usually ising a reducer on ur stand pipe helps create the suction going from a latger to a smaller size.also to break the siphon a snorkel helps. But restricting water flow is the best bet.

[Louise]

After some more experimenting, I think my siphon needs a snorcle. The snorkle-pdf seems useful, though I haven't had time to read it all yet. Also Affnans stuff seems reliable, much more so than my plastic-bottle-and-hose version. I'll just have to see if I can get hold of the right parts.

Thank you for good advice!

[Bob Campbell]

Did you try the air cap as I demonstrated in the video?

Louise said:

After some more experimenting, I think my siphon needs a snorcle. The snorkle-pdf seems useful, though I haven't had time to read it all yet. Also Affnans stuff seems reliable, much more so than my plastic-bottle-and-hose version. I'll just have to see if I can get hold of the right parts.

Thank you for good advice!

[Louise]

Sorry, Bob, I was reading fast, and missed your link. I'll dig into it, thanks!