Aquaponics - Cluster siphon success

I'm getting more and more confused by this idea of mine by the minute.

But anyway here's a simplified version of the Bullwinkle Siphon working at a range of different water flows. Possible advantages include not having to calibrate it, and perhaps using it in a solar or wind powered aquaponics system where there might be variable flow rates. Within reason it should start and stop without any trouble regardless of flow rate.

One of my better ideas.

Just to clarify, my idea is to have multiple standpipes in a bell siphon. As usual, as far as I know this is an original idea and blah blah blah. I give it freely to the world to make whatever use of as you see fit. Enjoy it, profit from it, hate it, etc etc etc.

By the way the mandarins are just there as packing to hold things in place.

That's all well and good, but this older version is driving me crazy. It should work over an even greater range of flow rates, and did on a few different occasions.

Intermittent faults drive me nuts.

Things should either work or not.

The first attempt at my anything in, anything out original recipe siphon, at least worked a few times. Now it seems I'm taking one step forward, and one and a bit back.

I made a new version of the uber siphon with a little more precision.

Only a little.

But I felt sure it should do what I asked of it.

I also made a nice clear top for the uber bell so I could see all the mini bells inside.

Brown tape is the new PVC.

To recap, it has a cluster of three bell siphons inside a forth.

The forth is set so that it's cut a little lower so that it triggers first.

The plan is that the forth siphon, the one without the glass jar on it, should trigger first, fill the big coverall siphon with water, and thus decisively trigger all the other siphons because of the increase in depth.

But on this version, the forth siphon didn't even trigger!

It's a full centimetre below the height of the others, and yet they all triggered. A tiny amount of water would trickle into the standpipe, then the large bell water height would drop, as the other 3 siphons triggered.

Now what this all means is that all I need to do is make a 3 into one siphon that has an air breather to break the siphon at the end of the cycle and all's well. The thing will do its job just fine as seen in the video, but it's driving me nuts that I don't understand what's going on with that forth siphon in the other version.

It turns out if you agonise over intermittent faults to my invention engine it groans in reply, "Occam's razor".

Go figure.

Cheese - Fine temperature control - double boiler

In my efforts to gain 120 new skills over the next 20 years, I have been so incredibly impressed, and utterly amazed at the generosity of everyone out there in internet land. It's as if all the world wants to do, is to help me on my quest to learn stuff.

Thanks internet.

Thanks all the world.

With some topics, I feel I've been able to contribute in some way to the body of knowledge. But in some, it's as if everything has been tried and tested, and then tried and tested again. It's as if the topic is sorted. Windmills spring to mind. No doubt there is still a lot to be done with windmills, but I suspect NASA might have more to do with it than someone like me.

I guess the age of the topic at hand has something to do with this. Aquaponics is probably always going to be easier to contribute to, than say, something like cheese making....

Cue dramatic music ........

I have something for cheese making.

There is this thing in the cooking world called a double boiler, and it's usefulness stems from the fact that water doesn't get hotter than 100c (boiling water) no matter what you do to it.

If you try to heat water hotter than it's boiling point, it cools itself by turning to steam and laughs right in your face.

"Ha ha!" It laughs.

What this means is you can stick a bowl over a pot of boiling or simmering water, and be sure you wont get temperatures any more extreme than 100c. In reality you are more likely to see temperatures in your bowl in the high 60c's.

But there are a few things you can do to get even more control.

And as usual if this isn't an original idea, I apologise, but as far as I know blah blah blah disclaimer etc etc etc ...

But it turns out, if you are trying to invent something completely unrelated, and take out everything from your kitchen cupboards, and spread it all out over the floor (again), sometimes you get some ideas. Some of them can even be good.

These ideas may not solve the problem you were hoping to solve, but may still be useful.

Cue dramatic music again........

Use a rice cooker. 

If you dont have one and you like to cook rice and are lucky enough to live the developed world, a rice cooker is a really good thing to have. 

It cooks rice.

Really well.

You should get one.

One of the cool things about a rice cooker is that it will cook your rice to perfection, then switch over to a "keep" mode, where it keeps it at a temperature hot enough to serve, but not so hot that it dries out. It can keep it at this nice temperature for 5 hours or something. Very convenient, as far as not needing to have good timing when feeding people.


Even more handy if you want to control temperatures for making cheese or something.

The first thing you can do is put some water in a rice cooker, and set it on "keep", instead of cook. This will get you a device that holds a temperature of around 46c. Perhaps suitable for melting chocolate or something. I don't know. But it could be handy. After all I have another 110 or so things to learn, so I'm sure 46c will be something I need one day down the track. Yoghurt? mmm yogurt. What temperature do you need for yoghurt...   Stop distracting me yoghurt.

The next thing you can try is placing a bowl of something on top of the rice cooker on "keep". This will get you 43c or there abouts.

High temperature rice cooker double boiler
But then, and this is the bit I'm most proud of, you can add three tapered chopsticks in such a way as to make it so the bowl rests on them rather than the rim of the rice cooker. Just jam them in between the bowl and the rice cooker rim, one at a time, but spread out evenly around the bowl.

Low temperature rice cooker double boiler
You can then slide the chopstick in or out to adjust the gap between the rice cooker, and the bowl you are trying to gently heat. This allows for pretty much any temperature you desire. All you need is a thick enough chopstick for the gap/temperature you require and you get total control.

The bigger the gap, the cooler the bowl of stuff. Just force whatever you can find in there that gives you the correct gap, and thus the correct temperature.

You can also play around with the water depth.

If you don't have chopsticks, you can use the ones you buy tomorrow!

Aquaponics - Strawberries!


I love strawberries.

And always get a little excited when I see the flowers.

I've been buying just one of each variety when I see them for sale to see what does well in aquaponics.  The very first plant I put in didn't do so well and died back, almost as far as it could before being called dead, but it's runners have all established and now all have flowers and fruit.

Strawberry plants get old and stop producing after a few years, so perhaps I bought an old plant. It was from a market stall so who knows what it was.

I've also bought a variety with, it turns out, a pink flower. I didn't know strawberries did that. This variety seems to be called Fragaria.

The other things I didn't know include the fact that strawberries are not really fruit. 

From what I can gather, the fruit is a fruit holder, and the fruit are these little pink protrusions that I think are flowers, or some other form of reproductive bit, and end up as a seed containing ovaries of the flower.

In a house I lived in as a kid, there was an uncared for strawberry patch that we discovered was full of hidden little strawberries that we would spend lots of fun time searching through.

These fond memories, and the fact that there were never enough of them are, I think, the driving force behind wanting to grow a lot of strawberries. Fresh home picked strawberries also make a very nice thing to be able to take to someone's house if you are dropping in for for dinner.

Grow some strawberries. Heaps of them. Kids love them and so do grown-ups. They don't take a lot of care, and if you grow them in aquaponics, they take even less. Just pull out any plants that stop fruiting when they get old. Or better yet, pull out last years and put them out to pasture in a wild patch in the corner of your back yard. 

They like plenty of water when starting out and when fruiting, don't like salt much, and the biggest threat to them is slugs and children. I believe they also like a pH closer to pH 6, but seem to cope with between pH 5.5 and pH 7.5, but found this difficult to nail down. It might just be different varieties prefer different conditions. 

Aquaponics - $2 sequencer proof of concept

I've managed to move a bit further along with the proof of concept $2 sequencer, by creating this $1 version.

When you look at the video, keep in mind the float has a hole running through it, and isn't round. It also has dents in it so it doesnt seal very well.

The shape of the bottles mean the float doesn't roll to the bottom. 

And to top it all off, in the video the float gets stuck on some brown packing tape as it's switching sides.

The entire thing leaks like a sieve, and only works one way because the float has an elongated end and doesn't settle into the other side.

There's nothing to stop it (except tinned tomatoes) rotating at will.

And my lighting and camera work leave a lot to be desired.

Other than those things, my selection of prototype materials is perfect.

If the float hadnt gotten stuck, was the correct shape, the bottles were a PVC tube instead, and there wasnt any brown packing tape involved, the float would then block the outlet on the left, and once the device became full again, would trigger to the right, swapping flow from one GB to another alternately. 

Normal, real world operation would see the amount of water flowing in, equal the amount flowing out. This would keep the ball afloat and off the outlet at the other end until the pump was turned off. 
Each time the pump turns off and then on again as decided by a timer, the device would switch sides.

To make certain the flows match, it might be necessary to create an overflow for some water so we can put slightly more into the system than the outlets can deal with. The rest could be designed to overflow from a point in the funnel section where the water comes in, to a point near each outlet. This way the float would stay above the water inlet until the pump was turned off. The majority of the water flow could exit via the overflows if required, with the amount entering the device only sufficient to tilt it, and keep the float from sinking and sealing the hole.

In the real version, my $2 sequencer would be made of PVC, and have a float only a bit smaller than the diameter of the PVC. The holes would be larger as well, so that the float sat further in, committing them to seal better.

I think this proof of concept is successful enough to indicate I should make a real one. 

I'm pretty sure it will work.

Currently my biggest issue with this device, is that I have no use for it. 

Others do though, so it must be made.

[edit from the future - There is some additional material on sequencers. Readers might find this newer version in a post titled  The Bullwinkle sequencer build of interest. It's a better design, and only costs around AU$15 to build with off the shelf PVC components]

Aquaponics - $2 sequencer

One challenge people have when designing an aquaponics system, is to make the best of the containers you have. This can sometimes mean getting by with a sump that's not quite big enough for a fish tank that nearly runs dry because you have a lot of garden beds.

One solution to this is to use a sequencer. This is a device, that through one method or another distributes water, first into one grow bed, then into another. This allows a better ratio of grow bed filtration to fishies supported because as one bed is draining back into your fish tank, the other is filling.

When I was testing The Invention Engine the other day, trying to come up with a slow flow siphon, I came up with another question that I thought would make yet another test.

I wanted a better sequencer. One that was more reliable, and much cheaper and easier to make.

I've so far made two different designs.

My first sequencer used a balance beam approach, the second, externalized sequencer, used a sprinkler, the third uses offcuts of, you guessed it PVC, a ping pong ball, or foam craft ball. I don't know what a craft ball is for but you can buy them at craft shops and they are a ball made of polystyrene. They cost a few cents each. I bought some a while ago to make coconuts. I was invited to a Hawaiian party and went as a palm tree.

So here's a thing about the universe....

If you get something that floats, but fits snugly in a hole in the bottom of the vessel , it stays stuck to the bottom by water pressure when you fill the vessel, even though it really wants to float to the top.

Here is a very rough proof of concept.

[Note my poor neglected cluster siphon sitting in the bottom of the sink at the back right.]

What this means is that if you had a vessel with a hole at each end, and a floating ball inside, you could hold it up empty, and the ball would fall to the bottom and sit in the hole. Now if you fill it with water, the ball will stay down and allow the vessel to fill up. Or should do.

If this happens, the vessel could be balanced in such a way as to tip when it became full. This should be possible, because the ball at the bottom would displace more weight of water than the ball weighed. The vessel gets top heavy, and tips. It then empties out of the hole in the other end. As the water is emptying, the weight of the inflowing water maintains the commitment to spill water in that direction, and through that end. The ball comes away from the hole it was in, and floats around for a bit. If you stop adding water to the vessel, the water drains, and the floating ball now should sit in the hole at the other end of the vessel. When the water is turned back on, the operation repeats, but in the opposite direction.

Take 2 PVC pipes at 200mm length.
Add a T junction pointing up in the centre.
Cap the 2 ends and drill holes in the end caps that roughly match your water input (you could add taps)
Add a foam ball into the tube that is a bit smaller than the diameter of the pipe.
Add a mesh so the ball cant escape out of the top of the T junction, but water can still flow in.
make the device balance (roughly) at the T junction.

Now add water flow from your pump to the top of the T junction through the mesh. (you might need a simple overflow coming from a hole in each side of the section of T pipe that goes up, running parallel to the main pipe to make it so you can size the holes to keep the water level at roughly the T so the ball doesn't block the end too soon)

Every time you stop the pump for a few seconds, the device will drain, the ball will block the draining hole, and when the pump comes back on, the device will tip to spill water from the other side.

Approximate cost...    
 $2 - $5

Approximate coolness if it works...    

[edit from the future - There is some additional material on sequencers. Readers might find this newer version in a post titled  The Bullwinkle sequencer build of interest. It's a better design, and only costs around AU$15 to build with off the shelf PVC components]

Aquaponics - Any volume in, any volume out cluster siphon progress

This has been a real eye opener.

Perhaps my eyeopeningest "thing" of my 120 things in 20 years yet. At least within aquaponics. I have to say moving enough electrons to make a light glow was pretty cool.

Anyway, I felt reasonably comfortable with my understanding of the bell siphon. I thought I understood how it worked, what caused it to trigger, and what caused it to stop.

It turns out, I have no idea.

This thing's a total mystery.

It wouldn't be the first time something made perfect sense, but went un-noticed by me.

What I thought I'd do is be very clever and make a cluster of siphons.

There is this phenomenon where, when a bell siphon triggers the height, or head, of water can actually rise above the height of the surrounding depth.

I figured this would allow me to make a device that had a cluster of  bell siphons, that would be force triggered by an uber siphon.


Picture this... get a bell siphon, and fill it with smaller bell siphons.

The original standpipe would be the lowest. The bell surrounding this would also encompass all the other bells for each additional siphon in the cluster

I tried a device with 4 standpipes. This took just under an hour to build and most of that was looking for the parts.

3 of the standpipes had a mini bell, the 4th had a maxi bell that covered all the bells. The 4th standpipe was also slightly lower so that it would trigger first. This 4th standpipe was the one that didnt have a private bell on it. (unseen in the photo behind the glass bells)

The plan was, the 4th standpipe would fill first. This would drain the uber bell of air and actually raise the water level above the other standpipes. This would in turn, of course, decisively trigger them. (this worked)

What this would mean is that a tiny flow (enough to trigger only one mini-siphon) would instantly trigger all 4 siphons. It would also mean that the drain would be so fast that the siphon would shut down in a very decisive manner, because it would be effectively pulling four times as much water as it might be if only one siphon were involved. To aid the shut down there is an air breather pipe (seen sticking out on the left) with the other end inside the big cover all bell. The big cover all bell is not shown because it blocks everything else, but sits so the bottom rests at the level the small breather pipe on the left meets the brown tape.

Most importantly, if there was a flow anywhere greater than enough to trigger 1 siphon, and less than the amount 4 siphons could cope with, this system would start and stop very decisively.

In a few trials, the system worked perfectly. I could trigger the system so that it started and stopped repeatedly with a flow rate of ...

2.5 seconds to fill a 500ml jug (my laundry tap on full)

And the same siphon also triggered at...

39 or 29 (it's hard to read my note)  seconds to fill a 500 ml jug (my laundry tap on a trickle so that the stream was breaking up before it hit the jug

So it worked. It worked over a massively variable flow rate,  and I'd made some kind of revolutionary new device.

But strange stuff happened all the time when I tried to reproduce the results.

I couldn't do it.

Sometimes it would work, others not.

Keep in mind, this thing was made of blutac, wire, and brown packing tape, so there is a fair chance I'll be able to refine it, but in short, I'm left feeling that I have much less of an understanding of the dynamics existing within a bell siphon than I thought I had before I started. The siphons didn't even always trigger in the same order.

I hate it when that happens.

I love it when that happens.

The true value of the scientific method is that it can show you that you know less that you thought, or you are just plain wrong, just as easily as it can show you how fabulous you are. An independent judge of fabulousness!

Valuable, but never comfortable :)

We live and learn.

My next step, is of course, to figure out what's going on, and make this device work.

When it worked it was a pretty impressive thing to watch, and much too valuable to give up on.

Wheels within wheels.

Or at least bubbles within bubbles.

Way cool.


Aquaponics - Any volume in, any volume out bell siphon

For my next trick, I'll attempt to make a bell siphon that triggers no mater what flow rate is applied, and then stops decisively.

I'm not entirely sure why this idea needs inventing, but it might be useful in a windmill powered aquaponics system, or a solar system without any battery.

Who knows.

My last post got me worried about the thought that I might "invent" something and claim it to be original even though someone else has already done it. If I didn't know about deer scarers, I might have eventually come up with the idea and presented my new idea to the world only to look like I whacked a 6000 year old monk on the head and ran off with his blueprints.

I'm not really sure what to do about this, other than to say I'll never knowingly claim an idea if I know it already exists. But, I'm not going to spend my life searching and checking patent records to make sure that it doesn't already exist. It's not as if I'm selling anything, and I have too many ideas and too little time to expend that much effort. I guess it doesn't really matter to anyone else but me, so you are probably finding this paragraph to be one of my more boring efforts.

So, I was thinking about buying a new pump and making a new system, but I thought I'd try to power it with wind energy, heat it with passive solar hot water, and perhaps make it a snail farming version of aquaponics. It's a pity I cant make a cow-ponics system in my suburban back yard, because then I could also grow some cheese in it.

Sadly, I couldn't figure out a way to add self promoting links to the handmade fishing lures, and mold making sections of my blog.

So, anyway, snails have the ability to seal themselves up for a few days if the pump isn't doing a lot so a flaky home made system powered by the vagaries of the weather will be more likely to work with snails than fish. The pump would only need to supply enough water to to keep the bacteria happy.

With this in mind, my pumping will be an extremely variable thing. So what I'll need is a siphon that triggers no matter what I put into it, and then stops no matter what as well.

That's a lot of "no matter what's".

I have a vague idea here, but really don't know if this one will work, so whatever you do, don't be telling anyone of my amazing breakthrough just yet.

I wont be.

Aquaponics - Ultra slow flow siphon solution

I came up with two solutions to attempting to make a small bucket that takes an hour to fill, but then dumps quickly, as discussed in the previous post called "Aquaponics - Ultra slow flow siphon problem".

The first came through a deliberate approach with a tested methodology, the second came because I recognised the first as already existing. (It made me think of another problem, leading me to find another solution, and that looked a bit like a deer scarer)

It's a deer scarer.

Actually the first solution is also a solution for some other problem, so I think I'll save it for solving that.

A deer scarer works by having a tube pivoting around a point roughly in the centre like a set of scales. One end is blocked and made slightly heavier. The other end is made slightly longer. Everything is set up in such a way as to make the thing sit with the open end up.

If you add a trickle of water to the open end, it eventually fills the tube. when it does it reaches a point where the water in the longer end overcomes the extra weight in the heavy end, so it tips.

Thanks for the use of the pic Cassiopeia_sweet
It looks like this.


Once the water is dumped, the heavy end thumps down onto a stone making a pleasant (yet apparently scary to deer) sound, that eases you into the now.

My version would be quiet.

My version would also be less graceful. If you made it out of 200mm PVC tubing you could dump a bucket full of water each time in a short compact unit. You could also place it somewhere else and pipe the sudden dump of water to your grow bed.


To make a grow bed flood for most of an hour, drain suddenly, then flood again, this might work.

Create a bell siphon that has a standpipe too large for your pump's flow. This will mean the siphon wont trigger, but the standpipe will allow water to circulate back to the fish tank or sump just by normal overflow through the standpipe. In other words, it will act as a constant flood grow bed.

Next mount a deer scarer above the siphon and divert a trickle of water from your pump to it, so that it tips once an hour (add a tap on the outlet for adjustment).

The sudden rush of water into the siphon area will be enough to decisively trigger your oversized siphon, draining all the water in mere moments to everyone's delight. So now we have a "mostly flood, and some drain" system. We also have an interesting, steam punk, bit of low tech kit moving around, rather than the sedentary vista provided by a constant flood grow bed.

This could be configured so that your grow bed drained every 12 hours or any desired time, making sure you had no dead areas of rancid mush hiding in the corners of your (almost) constant-flood grow bed.

Thanks Japan.

Thanks deer.

Thanks Nom*.

*[note from the future - someone has created an excellent example of just how such a thing might work.
and I love it when someone goes to the trouble of making something out of clear plastic just to show us.
Thanks for the heads up Nom. ]

Aquaponics - Ultra slow flow siphon problem

For some time now I've been working on an approach to invention and problem solving that, in my house, has become dramatically known as "The Invention Engine". It's a formalized structure to problem solving, and so far it's been working very well. It's all in my head at the moment, but at some stage I'll put it out to the world in some form. I'm testing the process again by finding a solution to triggering a siphon with an ultra slow flow.

In some recent trials, it looks like there may be some advantages to a constant flood grow beds, rather than flood and drain. This relies on having highly oxygenated water, but you should have that anyway because that's what your fish like. Some plants prefer flood and drain, but a lot seem to enjoy constant flood.

I can't help but think that one potential downside to constant flood, is that there may be areas that could  become stagnant. Flood and drain, on the other hand, pulls all the water out on each cycle, so there are no areas that miss out on turnover with new water. My fear is that it might be possible that constant flood could leave some areas to could go rotten over time.

I thought I might make a grow bed that was constant flood for most of an hour, drained once quickly, then have it repeat that pattern for ever.


Constant flood works by having a standpipe sticking up through the bottom of your grow bed at the height you desire the water to sit. You pump water in constantly, and it overflows into the fish tank via the standpipe.

So my solution would be to put a bell over the standpipe, but with an oversized standpipe that would be too big for the flow, so that it didn't trigger.

Now all we need to do is introduce a new, quick flow of water once every hour to trigger the siphon.

The Invention Engine first casually mentioned I should just put a second pump on a timer, and have it supply the hourly additional dump of water. I told it that a solution like that was too easy and expensive, and really needed a rethink.

I added the following parameters...

1. that it should require no additional pump
2. that it should require no electronics or timers

The Invention Engine suggested I divert a flow of water to a bucket sitting over the grow bed, put a second bell siphon in it, and have the water dump quickly to trigger the main siphon.

"OK" I  said. But how do you make a siphon that takes an hour to trigger, but still delivers a rush of water to the grow bed. A siphon with a very slow inflow can only trigger if it had a very small standpipe. Any flow that took an hour to fill a bucket, would only trigger a tiny siphon, and only deliver a tiny amount of additional water to the grow bed. A tiny additional flow would mean some very accurate calibrations to make the grow bed's main siphon trigger. In fact it might not be possible, and would definitely not be reliable.

"Make it huge" The Invention Engine replied.

"I want it small" I insisted.

"Oh" said The Invention Engine, "A small bucket that takes an hour to fill, but then dumps quickly?  That's a different question altogether".

Snail farming - Snail deaths

I hoped to be posting about egg laying today as my snails were due, but sadly there are two dead snails in my collection.

For reasons un-known even to me, they look like they might be the two that I found mating on my front lawn. It was these that I thought should be laying eggs today.

I have no idea what may have killed them. Perhaps they were in poor condition in the first place, or perhaps I failed to feed them some special food they needed.

I'll do some more research.

Aquaponics - Silver perch scale damage

My fish went on some kind of crazy bender last night. It's as if they threw a party I wasn't invited to.

The tank was trashed with the thermometer flung casually in the middle instead of hanging neatly on the side, the half terracotta pot I recently renovated for a hide was on a crazy angle, and no longer sitting on it's side. Someone had even thrown the TV out of the window*.

The medium sized guy that in the video spends quite a bit of time sitting second from the right, seems to have come off a bit worse than the others. He looks like he tried to scale himself. Some of the others have some dents and bruises as well.

It's left me with with a decision to make, because they almost certainly injured themselves on my terracotta pot.

If they got harassed by a cat or something, they need the cover as it may well have saved them, but if they just went on a bender and ran amok for a bit, I should probably remove the terracotta pot for their own protection.

It's also possible that they are outgrowing the pot and I need a bit of a rethink. It could even be the fact that I knocked out the base to make a tunnel rather than a cave. This allows them to swim right through it. Perhaps some are swimming through too fast. A cave shape might force them to enter a bit more gently, or reverse in or something.

*TV story is a likely reconstruction, and may not have occurred exactly as depicted

Snail farming - sophisticated snail breeding containment saucepan

When I found those two snails making out on my front lawn, I moved them into a container with a narrow, clear plastic tub of dirt (cut from a drink bottle). This was in the hope that when they laid eggs, I'd not only be able to see them digging down, but I might even be able to see the eggs through the side of the clear plastic tub. If I get really lucky I might be able to actually record them in the laying process.

If all goes well, they should be laying within the next 2 or 3 days.

The soil is a rich but well draining soil from my backyard. I hope it will be suitable. At this stage I have no idea what they really like to lay eggs in, but anything that has conquered the world like the garden snail cant be all that fussy.

The snail on the rim of the plastic tub (at 3 o'clock) seems to be spending quite a bit of time in the soil section so it may be looking for a good place to lay some eggs. I foolishly didn't mark the two I found on the front lawn so I have no idea which ones I can expect to lay eggs.

I've also been collecting whatever snails I can find and adding them to the beginnings of what will one day be my snail farm.

Sophisticated snail breeding containment saucepan
Currently, my snail farm looks a lot like a pyrex saucepan.

Some thing's look like other things by coincidence, but on this occasion, my sophisticated snail breeding containment device looks like a pyrex saucepan because it is.

I dropped a stack of alf-alfa seeds into their home, in the hope that snails would eat them when they grew, but over the next week was surprised to discover they had no interest at all in sprouts.

It was my hope that I might be able to use alf-alfa as the main food source, but after seeing how quickly lettuce gets devoured, I think it will be lettuce in the snail farm after all.

Currently my wild-collected snail farm population stands at forty. These are made of various sizes ranging from 10 mm, to about 27 (measured from side to tip of spiral)

Aquaponics - Bell siphon sizing not-so-magic formula

A "bell siphon" is a device that automates the flooding and draining of an aquaponics grow bed, even though the pump is adding water to that grow bed constantly. 

This post assumes you know lots about bell siphons. If you don't, you should start here on this post titled "bell siphon".

You probably should have already read this post titled calibrating a new bell siphon.

If you still don't feel you know enough, you might like to read this on flood and drain, look at this upgraded animation of a bell siphon working, watch this video of a glass bell siphon showing what's going on inside, or just skip this post and look at this youtube video of a panda cub sneezing. (personally I'd look at the panda)

It also assumes you don't mind reading something you think will eventually have an answer, but may disappoint.

Before you take anything I say to your design, you should know that my system is run with bits of string and bubblegum holding it together. 

My pump looks like this. I love wire.

Yes, those two opposing loops of stainless wire are the front bearing for my pump. Wire is the only thing supporting the impeller. It's been running that way for 6 months or so, but the output of the pump isn't really enough to run my system. The impeller is the wrong one salvaged from another pump, and doesn't really fit. 

There is no magic formula for weighing up the dimensions when designing or trouble-shooting a bell siphon, but there are some things you can do to make it a bit easier.

The problem, in a convoluted and sprawling nutshell, is this.

There are a huge number of variables in the way the water flows into and out of an aquaponics system. The type of pump you have is a big one, as is the length and width of your standpipe in the siphon itself. But there are other variables that can have dramatic effects. 

So, things that vary input...

  • pump output
  • height the pump has to pump up to (most mumps are labelled as if the user is going to pump water to nowhere. A pump labelled "3500 litres per hour - Max height 5 metres" might pump 3500 litres if there is no hose attached to it, but add a 5 metre hose and it will only pump 1 drop per hour. The amount it will manage at any given height in between are anybody's guess unless it comes with a graph indicating approximate values at different heights.)
  • restrictions to flow caused by corners and other bits that people use to distribute the water around their grow beds.
  • total length and diameter of hose used (there is a surprising amount of friction in shifting water through pipes)

And things that change output from the siphon, and how the siphon triggers might be...

  • width and height of bell
  • width and length of standpipe
  • freedom of water movement through the media and media screen (if you are drilling holes in the media screen, drill them all at the bottom - if the holes at the bottom cant drain enough, the ones at the top are not even going to be in play when the water level gets lower. The end result is that some kind of equilibrium can be reached where water coming in matches water going out through the siphon. In this case the siphon wont ever stop.
  • any obstructions to the outlet (uphill sections that might trap air or water, end of pipe being submerged  or anything else that might cause some back pressure)
  • changes in width of the outlet. Things like a flange that your stand pipe crews into may well restrict otherwise change the flow. Sometimes a bit of chaos in the standpipe can help create the seal required to trigger the siphon.
The result of all this, is that it's very difficult to say "this size siphon will work with this pump".

Even if you set up two systems with the same components, it would be a good idea to have a tap that will allow you to divert some water so you can fine tune your system. The irregular flow of water can mean some very small changes can have some big effects. 

So, the solution...

Of all these things, the easiest things to control, and thus the best things to start adjusting are...

  • Inlet flow. By adding a tap, and diverting perhaps 20% of your water back into the fish tank rather than the grow beds, you have some room to play. ie you have some spare water flow in hand, you can adjust your flow UP as well as DOWN to tune your siphon.
  • Outlet flow (Standpipe width) The standpipe is a very inexpensive component, and may even be sourced as an off-cut for free. This means it's easy enough to replace with a bigger one if need be, or filled with a smaller one.
My process for setting up a system would unfortunately involve a bit of essential trial and error.
  1. Buy a pump capable of turning over all the water in your fish tank ever hour plus 20% to divert. The diverted water aids in aeration so isn't wasted. (very important for your fish and filtration so pump selection should always be the starting point)
  2. Plug it in and look at the flow. 
  3. Get hold of a tube for a standpipe that you think will be big enough to dump more water than the pump puts in. My pump runs constantly and takes around 20 minutes to fill and 20 minutes to drain. That means my siphon can dump water at around twice the speed that the pump can deliver it. (see photo's below)
  4. Adjust accordingly. Its easy enough to adjust upwards, just drill a new hole and put in a bigger pipe. Downwards is also easy because a large number of hoses and PVC tubes fit the next size down inside them (I presume so you can join them). If you add an inner tube to reduce the width, you don't need to silicone it in place, because it doesn't matter if it leaks. Any leakage is just going into the original pipe anyway. I made mine bigger than I thought I'd need with this in mind. If you really feel the need, it would be easy enough to test it in a bucket. Plug the standpipe and fill the bucket, then let the water flow. If the pump cant keep up with the draining, then you will have no problems as you can always reduce it if you need to. 
That's the magic formula "Its easy to change the inflow and the outflow, so dont worry about it. Just have a go."

Just trust your judgement and as long as you have the tap between the pump and the grow bed, allowing adjustment, it will almost certainly work. If you are making your own system, you already trust yourself anyway, so just go that one step further, and do it. You'll be fine. And perhaps reread calibrating a new bell siphon.

Just out of something bordering on interest, my system runs like this. 

My inflow is from my very sad pump, and flows at around 50 seconds to shift a litre to the grow bed.

So I think that means I'm pumping 72 litres per hour. Which isn't really enough but that's the pump I have. 

I'm getting a new one. 

My standpipe was originally 19mm poly pipe but is now restricted to what my trade quality fridge magnet tape measure tells me is roughly 12 mm internal diameter garden hose.

The rate of outflow is really difficult to see in my real world system, because it drops straight down and doesn't photograph well, so I faked the output in my kitchen sink for the photo. It would look a little like this if I pointed my standpipe outlet to the side.

I warned you it might disappoint. 

If you are technically minded you might want to look at this 

I'm not, but I'm told it might be useful.

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