Backyard Aquaponics
A place to discuss aquaponics

The breather hose provides a bit....when I was doing tests, I used a small length tube as well, the difference in water flow through the 40mm pipes was:
Long tube 6,000lph
short tube 5,000lph
(when I say small, it was about 50mm long, just enough to get water flow before dragging in air)

...this is not a great difference when only emptying 100-200 litre GBs, but the air injected by the venturi did slow the water flow...it was one of the experiments we did (way back when ) when 1st testing the capabilities of the bell siphons (think it was one of Steve's tongue in cheek remarks that conned me into trying it )

I have 600L beds.
would you in your infinite wisdom, suggest a breather hose, and if so, what size?
10L/min is not that fast... hummm atm with loop siphons, I get a 600L bed empty in 5 minutes. so, 200L of water in ther we'll guess, that's 40L/min... I was hoping and under the impression that bell siphons were faster...

Whoa!!!!! my math is WAY off today... 100l/min that's more like it... ok I feel better now.
ignore that last...
just tell me should I build in a breather hose?

We had problems in breaking the seal on the bell siphons and what would then happen is it would go into equilibrium...outflow = inflow.

The air tube was put in to make sure the siphon seal was broken, some are getting away without the air tube, I know the siphons work efficiently with the air tube and so always use one...my bell siphon setup has been going almost 2 years now.

I use 3mm air tube and run it to within 25mm of the base of the bell cover, some have tested and used up to 12mm...but 3mm works for me

If you have a look at the 1st post on this thread Kuda, there is a write up and some pics as well that might help you...1st post in Oct 2006 and it was up and running before then - so nearly 2 years

Kuda - you are correct that I was initially using Bella without an airhose. I did find though that when I incleased the length of the horizontal pipe running from the siphon to the sump Bella was not breaking any more. To fix this I added an air hose again. I'm inclined to have an airhose with all my future Bellas. It just provides wider parameters within which the autosiphon will work.

OK thanks VB, clears that up... I'll be adding one then

Dear ELLKAYBEE I'm new to this forum and have been reading about bell siphons. Yours is a very neat design. I was wondering if you need to put a u-bend/trap under the standpipe to lock the siphon for a better starting characteristic. Also can you adjust the dump by moving the airvent/tube end higher or lower so the siphon breaks sooner/later. Thanks for the help and have enjoyed your posts. Doug Barr

Doug - welcome to the forum...you can put the u-bend anywhere from straight under the GB to right at the end like I do...I found it easier to put on the end and it worked better there.

The air tube doesn't break the seal until sufficient ( a lot of) of air has been sucked under the siphon pipe....when air is sucked under the main pipe, it stops the water flow but because there is more water being put in from the fish tank and water still in the GB, water flow through the siphon ceases to move...it is then that the air being sucked in through the air tube breaks the seal and allows the bell siphon to fill with air

Water then rises above the air tube inlet and air ceases to move into the bell siphon( by now it should be full of air and water fallen back to natural levels) and the water in the GB rises and forces out the air , thus starting the siphon again when it reaches the top of the cover.

No...raising or lowering the air tube will not cause the siphon to break sooner/later...it could cause malfunctions if it was too low (stopping the inside of the bell siphon filling with air) or too high (not letting the siphon start working)...but it needs to be pretty high to do that

hello
i have a question

i don't use bell siphons, just bell standpipes, kind off continious siphon
i didn't want to use bell syphons because i wanted to have more water volume with no sump tanks or whatsoever, just FT and GBs
in my early experiments i noticed that larger volumes of water contain more O2(duh:) and have higher temp. buffering capacities

so i have 1000Lt of FT water and 640 Lt at the GB, that's 1640Lt all togheter, that's why i can't use bell siphons, it would overflow my FT, but i could make them run on random times not all togheter --> that would solve part of the problem

still, using syphons means that u gotta run the pump 24/7 right? or at least on short intervals else your GB medium can get dry(you can't know on which point the siphon action stops when you stop the pump-without a float valve)?

or is the main reason here to double the drain flow to remove the solids as much as possible?


good day

Molj, I have a single ~700L growbed full of hydroton and a 2000L fishtank. I use a 1800L/h pump that is continuously on (probably about 800L/h at this head), and a 32/50mm bell syphon. The syphon cycle is about 10 minutes filling, 5 minutes draining. The water goes up and down about 7cms every cycle, which means that the 700L growbed only holds 250L of water (a third). Remember that your growbed media takes up a big amount of space, and also that there's always a couple of cms of water remaining at the bottom when you use a bell syphon.

So in your case, if all the syphons align the water would go up and down maybe a total of 15cm, which (I think) is not much of a problem.

Using syphons means that you need to run your pump 24/7, but you I believe somebody put the pump on a timer so it only runs half of the time at night. Indeed you can't control the level of the growbed by switching the pump on and off (without a float valve).

I think the main reasons for the autosyphon are that it's a quite simple concept (no moving parts, no fancy electrical systems), the pump can be on 24/7 (most pumps last longer that way) and it keeps your bacteria and ft oxygenated.

those 600 liters of mine are just water not rocks included
it would make sense so that u can use smaller pumps, low inflow big outflow

my pump moves the hole water around in 10 mins, so i don't have to run it 24/7 for O2 reasons
each bucket gets ~300 l/h(16 gbs, each 100L - 40 L water)

i guess i'll see how the solids move around, else there will be some work again

1600L is the actual GB volume

In that case it would be around 60cm (you have an IBC for ft, right?), which is quite a lot.. But with that many growbeds, the water level would rarely get to +30 or -30cm or even +15 or -15cm; there's only a very small chance that a lot of syphons align. Your fish tank is deep enough, so I don't think it would be much of a problem to use syphons without a sump, but your average ft water level would be at 30cm under the top so your fish only have an average of 700L of ft.

Anyways, good luck whatever you do!

you'r right(yeah i have an IBC) and you'r right on the second thing too, got my head jumping too quick before i actually calculated a lil bit, thank you and good luck to you too

Hi NewageMnfarmer! That makes at least three of us here from Mn. I'd love to see what you're doing, do you have a systems thread going yet?

I must be learning. I just rewatched that video NewageMnfarmer posted, and I think I finally understand bell siphons!

Superb posting EKB. Thank you!

Quesion: Is a bell siphon simply a venturi drain with a cap on it? The cap precludes the need to have the outer pipe above highest water level. (?) Am I missing something?