Aquaponics - Building a better air lift

Just because I've never seen my blog being poked with a pencil on youtube before, I thought I'd reply to this via a post...

This is a comment by Mike Creuzer on my post about a new air lift design I'd been thinking about. It looked like this...

The water level will be the same in the air-stone line as it is in the upper pocket. Air won't try to go up the tube until it reaches the bottom of it. (that's a lousy sentence, isn't it?)

How about a video? I like videos. Take a look at and see if I explained my thoughts clearly enough (probably not)

That's a good point.

I think if the secondary tubes were removed, the water level will be pushed down by the accumulating air pressure in the chamber. and eventually underflow* in to the next air lift all by itself.

But now, after hearing Mike describe what's happening, I'm a little troubled by the way the air is expected to  travel down into the chambers. I think this means that the operation will be stop start. (which might be ok - see the future)

This post from BYAP forum from me might explain it better...

Post subject: Re: Low Energy Aquaponics - LEAP Posted: Tue Feb 14, 2012 2:57 pm...

That wasn't so much as a design, but rather a vague notion. If I was playing with it, I'd probably start with making each step overlap by around 75%. ie in an IBC with each step being 100cm, I'd make the first lift from ground level to water level, the next from 25 cm off the bottom of the IBC to 25 cm higher than the water, the next from half way up the IBC to 50cm above the water... that kind of thing. But instead of 25cm, I'd use whatever height the first step could lift a decent amount of water to, above water level.

Then if I could raise more water higher than the a single straight air lift, it could be considered a worthwhile thing to have learnt. If I couldn't, I'd consider it a worthwhile thing to have learnt. 

But it all depends on exactly why it is that the lift works. If the air is just acting like a piston and pushing water up, then I doubt it will work. But it the air water combo is floating on the surrounding water because it displaces more than it weighs, then it might. Actually, either way it might.

Or not.

But, only a 5 minute test with a length of poly pipe, 3 elbows, 2 air stones an air pump, a 1L jug and a stopwatch will tell.

If I don't know the physics behind something, but have a vague notion, I knock out an invention for each vague notion, because sometimes they can generate a different approach. eg If it turns out water/air combos dont float, how can we make them float... that sort of thing. Sometimes I dont even try to learn the physics, because it can restrict the thought process to one particular direction. I'll do the thinking, then do the research only after I've thought of as many different affecting forces that MIGHT be at play. 

I find as a result, almost everything is worth exploring. I think I've learnt more from things that didn't work than from things that did, but I think there is 15% chance that that idea will either work, or have some payoff at some point. Each new thing I discover about the universe and how it behaves makes the next thing that much more apparent an accessible, and I'm getting better every day with being able to pick the things that might lead to something.

I tend toward a test, after dancing with angels on pin heads for a bit. It's nice to know one way or another 

And this...

I thought this might be a good way to deliver air if the second hypothesis is correct. ie That an air lift works by pushing water up with the air...

The general idea was to create a PVC air trap, set at an angle and pivoting around an axle mounted on it's lid.

This would allow the device to dump all its air at once, but only when it became full, so that it would dump a lot of air quickly regardless or the rate the air was being added.

Re-looking at that original drawing of the multi-stage air lift, I don't think the chambered air tubes would be needed at all. The air would just dump under the side.

[The future]
I'm being told about something called a geyser pump that appears to work by dumping a large lump of air into an airlift all at once. Exactly how it does this is still a bit of a mystery to me, but I'm looking into it.

To be honest, this pressure stuff is a little baffling to me. I've never really understood pressure.

For instance...

For years I've always been puzzled by submarines, pressure, and waves.

If a submarine is at it's maximum depth, and then a 100ft wave goes over the top, does the sub feel too much pressure, and get all squished?


I have no idea.

I also don't really care, but I definitely have no idea.

This post is a mess. I'll do better soon.

*opposite to overflow**

**Yeah, that's a word now

If I was Santa, I'd still do 120 Things in 20 years, but I'd have all my helpers experimenting with building a better air lift for everyone's aquaponics systems. Only 318 sleeps to go.

1 comment:

  1. Well, fancy that... I got my very own blog post on one of my favorite blogs!

    I love vague notions. I have them all the time and run with them as well.

    I am thinking that your 'underflow' (thanks for defining the terminology we will use here) will be pretty constant as air will be coming into the lift station chambers at a fairly constant rate. The same way air wants to 'underflow' on a bell siphon before it breaks. Maybe a slot or hole at the bottom will give a smaller, more consistent 'underflow'? More bubbly?

    Who would have thought it would be so hard to convince water to fall up?


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