Aquaponics - Absurdly low energy system test result

I rigged something of a test to see if I could use my powerhead to create the zero head system I keep banging on about.

I'm not sure what the results mean.

It's very difficult to measure the flow when you can lift the pipe out of the water to check, but I think the test went some way to proving the concept.

When I turned on the pump I got around a 2.5 cm difference in water level between the grow bed and the the fish tank. I think that means that If I have a pipe joining the two, I should see all that head equal out. As it is I did have a pipe, but I suspect there was some air in it and I'm not sure how effective it was, but there was definitely flow.

Another major problem with my test is that I didnt want to break apart my powerhead. If I broke it and put the impeller into a tight fitting tube, I think I would move a LOT more water. As it was there was an inch of free space around the impeller where water could flow back past it the wrong way.




This video shows the pump being turned on at around 5seconds into the video, and it shifting 1cm deep of water from a completely full half blue barrel in 20 seconds.

So I think if I break the case off and commit to the design, I should be able to double my flow.

I made that double number up. Really I have no idea.

I think the flow I got was around 800LPH from a 12 watt powerhead, but as I said, there is a lot I can do to make it better.

for one thing, using a corrugated pipe is a bad idea, as is using siphons to go up and over rather than using bigger pipes directly connected. These were necessary because I didn't want to drill holes in the grow beds as I plan on using them differently.

I'll do some more tests, but for now I want to do a system expansion, and make a decent sized system that will feed us.



120 Things in 20 years, where we have industrial design standards, above which we will not go.

Aquaponics - Absurdly low energy system test

I started work on my absurdly low energy test system and it looks a little bit like this.

Actually it looks exactly like this, because this is it.

And that's all there is gong to be until tomorrow at least.

The grow media this time is a product from Germany called Hydroton. It's clay balls that are puffed up like popcorn and are really nice to work with.

They are very clean, so all they needed was a quick rinse rather than the hard work that washing scoria was all about.

They are also great to work with.

Scoria was very sharp, and hard on the hands, but this stuff is a very different story. You can push you hand right to the bottom of the grow bed. I'm surprised it's stable enough for tall plants, but it doesn't seem to pose any problems.

I've read that it can float for a while, and mine is sitting in a half full tub, so perhaps it will settle a bit in time.

Because I've been feeding close to the maximum my system would allow, I should be able to compare scoria to Hydroton from the point of view of the bacteria colony. If I cant double the feed within a few months, it means the scoria is better, it will be interesting to see.


120 Things in 20 years, where sometimes, eventually, stuff like an aquaponics, absurdly low energy system test can start to take shape.

Aquaponics - Powerhead zero head test

The absurdly low energy aquaponics system I've been working on, will probably use a power head to shift water between a fish tank, and a constant flood grow bed, both kept at the same water level so that the pump can run at it's most efficient.

To this end, I put a powerhead in a 90mm pvc pipe to see what kind of flow I can expect.

It definitely looks like being viable.

With only the tiniest head, the thing moved a lot of water. With a head of more than 2 cm, almost no water flowed at all, but I'm hoping to make a zero head system so it should work fine.

It's difficult to see the flow because I cant raise the pipe very much at all without stopping the flow altogether, but there is quite a bit of water fowing over the edge.

I would guess around 2000L an hour.

The flow at zero head with the pipe submerged is a lot more than this picture with a little head to overcome.






120 Things in 20 years, Aquaponics - Powerhead zero head test. I have an ear ache.

Aquaponics - New system expansion

In this first stage of my system expansion, I'll be using my existing pump and running a fairly conventional layout.

Half an IBC as a fish tank, and three, media filled blue barrel halves as grow beds with the existing fish tank as a sump, or perhaps 4 grow beds and no sump.

In a system with a sump, you maintain a constant height in the fish tank, by placing the pump in the sump tank, and filling the grow beds by having the fish tank overflow into the grow beds. The grow beds then drain back to the sump.

This type of system is often called CHIFT PIST (Constant Height In Fish Tank, Pump In Sump Tank).

Stage two would see me cutting the second IBC in half, and creating two media filled constant flood grow beds powered by either a new type of airlift I've been thinking about, a conventional airlift, a power head, or any combination of all these.

Or something else.

In short, the absurdly low power use system is still a little way off. The main problem I face is having to find a completely new form of media that will be ultra light weight so I can pick up and move a cubic metre of it. I live in a rented house, and may have to move it at some stage in the future, and a cubic metre of gravel might weigh around the same as a family car.

Currently, that media looks a bit like it might be soft drink bottle caps put through a garden mulcher, but it's early days.



120 Things in 20 years, where sometimes my aquaponics - new system expansions, simply dont happen.

Aquaponics - Absurdly low energy system

I've had an idea.

It's been a while.

I keep running the problem of a low energy system through what I like to call the invention engine, and it keeps telling me to lower the difference in height between the fish tank and the grow bed. Eventually it told me to make them at the same level, and use a powerhead to just stir water from the fish tank to the grow bed.

But when I run it with the new system design, it says to drop the grow bed even lower.

Into the negative.

Which doesn't make a lot of sense until you think about moving the grow bed back up again to drain it.

When I ran that through the invention engine, it came up with floating the grow bed in and out of the fish tank.

By pumping air under it.

An air pump is inexpensive to run, and I know it's already capable of the pressure required to get air to the bottom of a tank, because a lot of people use them in exactly that way.

The thing I dont know, is if it's capable of shifting enough volume to raise the bed often enough. It will definitely raise the bed, but if it takes too long, then it's not going to be worth it. I'm guessing I'd need to raise and lower the bed at least twice per hour. Dropping it back down should be easy to make quick, so as a target to aim for, I think I'll look at raising the grow bed within half an hour. 

So if I put a grow bed on another, inverted growbed, I can fill the bottom (upside down) one slowly with a small air pump, and effectively, float the grow bed up and down rather than shift the water up and down.

As the grow bed lowers into the water, it displaces water, causing the fish tank water level to rise, and thus contribute to submerging the media to the desired level. The reverse would occur when the air was trapped and the grow bed rises. It would displace less water, so the fish tank level would drop, resulting in a quicker low tide.

The air pump can be even smaller than I first thought, because there's really no need for all that pumping to the bottom of the tank, so no need for all that pressure. That combined with the way all that stuff in the previous paragraph should work, might mean it will be an absurdly low energy use aquaponics system.

I haven't worked out the down bit, but that wont prove difficult at all. I really enjoy inventing things where the force I'm trying to overcome is used to do the overcoming, so in this case I'd like to make use of the pressure build up to release itself, but even if I cant work something out, I can always use electronics to make a valve open at the top of the cycle, dumping the air, and dropping the grow bed back down.

I might even be able to use the rush of air to do something productive.

Cooling perhaps... who knows.

It might even be possible to use the incoming water from an existing system to get a free lift, by using it to force some bubbles under a new air powered grow bed.

Or to fill the grow bed, raise it, and then distribute the water to another grow bed, creating a kind of pump.

It might also need a few guides to keep it from wearing where the grow bed would inevitably touch the fish tank.

I have a really spooky feeling I've had this idea before, and this may just be a side effect of my current lifestyle (that being sleeping in a post-op haze) or could just be because I have had the idea before. Or it could even be confirmation of the sneaking suspicion, that whenever I have an idea, what I'm really doing is simply remembering having had the idea in the future, at some point after that.

This means all the invention engine does is jogs the memory I'm yet to have had...

yet

Either way it will work.

All it would need is a grow bed media that weighs less than the water the air displaces, and it will work.

And some buckets...

I'll need some buckets.

I'll make one tomorrow.

Buckets, and media...

I'll need some media.

Sleep now.


120 Things in 20 years, For all your absurdly low energy aquaponics systems and pre-think.