Backyard Aquaponics
A place to discuss aquaponics

and I want to make sure it isn't gonna fall apart on me

Fair call.

Hi Ell:
So this is what they call a "bell and siphon"?

Hi Dave,
not sure yet

Okay, this is the setup for the test, so we are all on the same wavelength – the “siphon pipe” slips over the “drain pipe” and the “down pipe” is submerged into the water.

I haven’t a pump as yet (size not calculated) so the water will be added by buckets to fill the top bin (grow bed) to start the siphon action, now for test 1:

Hi Dave/VB, didn’t mean to be as abrupt with my replies, my mind was mainly on how to test the concept properly and not concentrating on the task at hand.



Okay – Test 1 works

Run 1 – Added water (80 litres to top of siphon pipe), turbulence at bottom of down pipe then “whoosh” water drained from grow bed, must admit poured water quickly to make sure action occurred.

Run 2 – Added water slowly when up to bottom level of crenellations and got same action, the siphon seal has not been broken and so by adding water the siphon action continues (but that was expected – nice to know about these things and test for them).

Did another few more test runs and received the same results, timed the discharge 46 seconds to empty the grow bed, so now to Phase 2 testing.

Test 2 Setup
I am going to drill a hole in the down pipe just below the top of the elbow and use the 3mm tubing to break the siphon seal, will report back

Post count at 74 unread – this could be a long day

Fantastic! You clever bugger! This is great this thing.

Now, the siphon pipe, it is 1 cm above the drain pipe. This will function but not be clog free (or I'm missing something again). Is it possible to have the siphon pipe right to the bottom, and drilled, like Joel's standpipe, so you may keep gravel and roots at bay.

This design with crenellations, is this to allow a large volume of water in at once to begin the siphon? If so, wouldn't no crenellations do this better.

Scuse me if the questions seem dumb, trying to get my head round applying this to a bed for a test drive.

Now that I have thought about it I think Dave can claim naming rights "Bell & siphon” it is, now that’s more pressure to get this working.

AA - will get back to you on answers, just want to get through all my thought processing then sit down and analyze the whole lot including modifications but keep up the questions no problems

Test 2

Run 1
Drilled hole (5mm) to take tubing, ran test as is – wouldn’t start so put finger over hole until siphon action started then released – lots of bubbles = aeration and bin drained

Run 2 – fitted 3mm tubing and ran into bin, the level below the crenellations and the length sufficient so that it will not end in the gravel, the reason for this was to allow the air to escape from the drain pipe until the water level was above the tubing and then to cut off the air outlet before siphon action, a hole in the outer protective pipe (90mm) will be used to keep the end of the tube underwater at that point – see picture.
Oops – meant to move that high precision cutting instrument, makes short work of crenellations and in the hands of an experienced operator, small 5mm holes are a breeze, the lubricating material next to it comes highly recommended also.

This worked but if the water is poured very slowly the level continues to rise and siphon action doesn’t happen – well it will but not at the set height. Timed the drainage and it is now out to 60 odd seconds, this is due (I believe) to the air being sucked in (venturi effect) by the 3mm tubing, so how to get rid of the trapped air.

In all tests the amount of water left in the grow bed was <15mm.

Hmmn….WIPM time

WIPM (Work In Progress Mode) WIPM is invoked when:
a. you have a problem and need time to think of a solution (blaming the other bloke is not a solution)
b. you have the basic concept correct and now need to sit back and see if the design can be improved upon
c. ya wanna beer

WIPM © is automatically included with (a) and/or (b); or can be called on its own at any time.

AA – there will be 3 pipes in the grow bed

Pipe 1 (40mm) is the drain pipe that has the crenellations – these are required to allow the large volume of water and because of the height of them (12mm), water will be held back longer when compared to a 20 or 40mm horizontal pipe as in a U bend.

Pipe 2 (65mm) sits directly over pipe 1 and is 1cm off the base of the grow bed, the water flows up between the cavity of the pipes, the 1cm was arbitrary and can be increased if clogging is a problem, it was also used as a measure so that I could gauge the depth after siphoning was complete.

Pipe 3 (90/100mm) will cover both pipes and act as a shield for gravel and debris, holes (nah - lets use crenellations) can then be cut on the base of the pipe and holes drilled to allow sufficient water flow.

I’ll just type up my next test results and post shortly (and pictures)

Les

Damn - I was going to stay logged in and see how many posts are needed read but keep being automatically logged off

Test3 - Mod(1)
Drilled a small (3mm) hole in top of end cap.

Cut a piece of plastic to cover the hole, approx 10mm * 15mm.

Covered the hole with the plastic and put a bead of Silastic crosswise and smeared over the sides onto the end cap, the Silastic acts as a door hinge.

Theory – as the water rises the air which was trapped previously will push the plastic up and escape, when the siphoning begins the plastic will be sucked down and close the door.

The plastic needs to be reasonably thick and flexible, something like those plastic zip bags would be ideal.

Test Run 1
As the water level rises, and just before siphon action, air and a dribble of water escaped through the hole, this proved to be an added bonus because the water assisted in sealing the hole when siphon action started, time still around 60 seconds.

Part of the “Bell & Siphon” system idea is to easily dismantle it for inspection or maintenance even while in operation (except when actually siphoning) and so cut a piece of 90mm pipe to put over the contraption to see how it looks.

Now a 65mm end cap is actually 75mm in diameter externally, which means when reaching inside a 90mm pipe to pull out the siphon pipe means jammed fingers.

Mod(2) – drilled a hole in top of end cap and threaded some nylon cord through, tied a knot on the inside and slapped some silicone around to seal it.

Description of operation
Water flows into grow bed, as the air in the drain/down pipe compresses it is pushed out via the 3mm tubing until the water level rises and cuts off the air flow when the tubing is submerged.

The water continues to rise and the remaining trapped air is forced out of the escape hatch until siphon action begins and sucks the plastic piece back over the hole, when the water level falls below the 3mm tubing, air is sucked into the down pipe and aerates the water flowing.

Siphon action continues until air is sucked under the 65mm siphon pipe and water ceases to flow up inside the siphon pipe, but because air can enter via the tubing, as the water in the down pipe continues downwards it sucks in air which ensures a quick break of the siphon seal and so the cycle starts again. (or something like that).

My main idea is to empty the grow bed as fast as possible and although the aeration from the tubing is an added bonus it is slowing down the water flow and is not really required at this stage.


New approach
Instead of feeding air into the down pipe, use the siphon pipe as the air intake area.

Mod(3)
Blocked end of tubing already mounted with silicone sealant (great stuff this)
Drilled a hole in the side of the siphon pipe and inserted tubing into hole ran tubing down side of pipe and cut off about 5mm from bottom, 3mm tubing end is approx 15mm from grow bed base (infact did 3 separate runs).

Test run time now back to 45-47 sec hand held, this may not seem important but will cover this when I get to doing calculations of water flow in and out.

A further mod may be to increase the outer casing size from 90mm to 100mm, infact the "Bell & Siphon" concempt is open for scrutinisation.

Pipes from left to right:
Pipe 1 fits over Pipe 4 and Pipe 3 then goes over both – Pipe 2 was just part of the experiments.

Including a drawing of the escape hatch idea, it doesn’t show very well in the photo:

Double WIPM time, will relax until tomorrow morning

Les

Here’s the rub – in ideal conditions with no restriction around the siphon for the water, water will exit the grow bed at around 6000 litre/hour through a 40mm pipe.

Put the 90mm pipe on and access to the to the siphon pipe is restricted and air is sucked in prematurely but not enough to break the seal before more water seeps into the 90mm pipe which gets the siphon action going again but then it seems to cycle there (siphon stop/start) – too easy – use a larger size pipe and cut more access holes lower down and all will work again.

Now add gravel and the water will be further restricted and the problem will return, it is not the amount of water in the grow bed, it is the volume of water inside the outer covering pipe available to be sucked up.

So what is a solution? Has any body else had this problem using 40mm outlet pipe size?

I have thought of:
Increasing the outer pipe but will that be enough (even 150mm)
Putting in a false floor and have the water flow straight down then along to the siphon pipe but probably not practical.
Reducing the size of the drain pipe.

Suggestions welcome

Hi Ell:
Bell and siphon is one kind of siphon that you can find while Googling. I think the name is from the 1700s or before even.
http://www.siphons.com/operation.html

Hi

I a looking at your experiment. KEWL!

1) On the fist page you show in your first drawing a pipe with a lid! Looks very neat and simple! I can't see why it won't work.

2) Also may I ask if the crenulations are to keep the lid from touching the top of the inner vertical pipe.

Keep it up - good job in progress.

ahh Dave now I understand - thanks for that

j7au - yep, the pillars are to hold the lid up and the bits cut out are to allow the water to flow through, in actual fact, I got the idea from one of your comments about putting a custom lid over a pipe and you had a siphon and it kind of exploded from there.

Starting to work it out properly now and need a pump, gravel and some more pipe to proceed further - must admit it is very addictive

Why did I ever start

Les

Every time you learn anoher way not to do it you get closer to perfecting it.

Go like ell.

L, did you name that pipe "pyros" becasue it looks like a stick of dynamite ? LOL