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.

Genius.

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.

So...

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.
http://www.youtube.com/watch?v=GSXqr3VdYyM
and I love it when someone goes to the trouble of making something out of clear plastic just to show us. 
http://www.youtube.com/watch?v=4oS0mNApYqw
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.

Tricky.

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".

Animation - Bell siphon

I've decided to learn how to make animations so as to be better at communication.... And stuff.

Earlier attempts I have made were created frame by frame, but I recently nabbed a copy of Synfig Studio.

From what I've seen so far, It looks the goods. Its free to download and use and its all open source. Yet again the open source community has exceeded my expectations. All these people who contribute are truly amazing. Thank you all.

Here is my first attempt that actually worked. Depending on what I can offer, I might make animation or visual communication a "thing" because I'm sure I'll need the skills more and more, no matter what I do in the future.

The bell siphon is running with a continuous inflow of water. The siphon triggers when the standpipe fills with water. The grow bed (terracotta colour) floods and drains automatically, creating tide-like conditions for plants. The bell siphon is commonly used in aquaponics as a method to flood and drain grow beds. The water drains back into a fish tank, where a pump cycles it back to the grow bed.

A bell siphon (in yellow) triggering and draining via the standpipe (in green)

The real things looks like this from an earlier post called "Aquaponics - Glass bell siphon"



I just re-read this post and it doesn't sound like me.
But it is.
There, that's settled that.

Aquaponics - Glass bell siphon

It's been said before, even by me, that a picture paints a thousand words. So imagine how many words a short video paints.

I made a glass bell siphon in an attempt to discover what actually goes on in one as it starts to siphon. It involved taking a glass jar, and turning it upside down.

I think the key when building a siphon is to place a tap at some point on the hose coming from the pump to allow a small percent of the flow to be diverted. This allows you to increase or decrease the flow and makes making a siphon very easy. The most difficult thing to get right is to match the flow against the size  of the standpipe (the standpipe is the white PVC pipe the water drains out of the bucket through.

in this video...

• the siphon starts at around 00:20. Even though there is some flow before 20 seconds in, it doesn't really start properly until enough water is entering the standpipe to create the required suction)
• then stops at around 00:40. Note the rush of air in through the small hose within the jar and how quickly it stops the siphon. 
• then the cycle repeats. 

A bell siphon does that. It also generates a tide-like ebb and flow in the grow bed(s). This test siphon is in a small bucket, so the time it takes to flood and drain is only a few seconds. We could flood and drain as fast as this in aquaponics, but would then normally turn the pump off for up to an hour each cycle in order to let the plants breath for a bit. Alternatively we might use a smaller pump and run it all the time.

Aquaponics - Flood and drain

Plants seem to like it when their roots are not too wet and not too dry. Goldilocks would have us set the moisture level juuuust right, but in aquaponics, there is a better way. Flood and drain.

In our blue barrel system (pictured here at day one) we have half a barrel at ground level as a fish tank, and half raised above the fish tank as a grow bed (within the online forums you will see FT as fish tank and GB as grow or garden bed)
                                                                                                                

This allows us to pump water up to the grow bed and have it drain back down with gravity. But rather than have it running all the time the plants prefer to get some water, then some air, to their roots. One very simple way of doing this is to use an auto-siphon.

An auto-siphon allows us to fill the grow bed with nutrient rich water to a predetermined level, and then have the water dump back out into the fish tank bellow, exposing our plant's roots to the air. Plants love that kind of thing. And the fish love the circulating water. Keeping the water moving oxygenates it and running it through the grow beds filters it.                               

A bell auto-siphon would look something like this if someone were to make an animation of one working ...

- water is pumped in at the top from the fish tank (FT not shown)
- when the water level rises to the top of the standpipe (the standpipe is the innermost pipe) it starts to overflow.
- As the standpipe fills and the water flows down the tube and back into the fish tank, it forms a siphon.
- the small amount of air left at the top of the bell (the bell is the bit that surrounds the standpipe) is sucked down with the water and the grow bed quickly drains back into the fish tank.
- when the grow bed level gets to the bottom of the bell the siphon is broken and the draining action stops
- the water is always running in but the siphon is designed to allow water to flow out faster than it comes in
- the result of this is a flood and drain cycle that plants love.

Other beasties in the grow bed love this flood and drain as well but more on that later.