Backyard Aquaponics
A place to discuss aquaponics

I get this mental picture of the poor woman climbing onto the AP roof to hang up the washing and hearing a stream of profanities from G6 as the aerator stops.

Then there's the time when gale force winds hit Kalgoorlie, the little paddles are spanking the fish out of the tank for sixes in true Gillie fashion (sorry US APers - thats Aussie colloquialism )

Sorry G6 - got carried away a bit there, back to washin' gravel

Hi Gnasho,

Have you considered something like a Savonius Rotor.....connected to an Archimedes Screw.

"The Savonius Rotor has a vertical axis, is slow turning, and is a high-torque wind machine. It is well suited for pumping water, and its low speed makes balancing less critical. To make a Savonius rotor machine, cut a 55-gallon drum in half and weld the two halves into an offset assembly. The maximum efficiency for this machine is 15 to 18 percent."
(Source Unknown).

You can see a picture and learn more on http://sustainable-life.co.uk/blog/2005 ... onius.html

If the Archimedes Screw is too complicated to build, I'd have thought the torque capability of a Savonius Rotor would be more than adequate to power a small diaphragm air pump.

The Integral Urban House on the Berkley Campus of Uni. of Calfornia featured a Savonius Rotor driving a diaphram pump (pumping water rather than air). They used a bellcrank arrangement to convert the vertical rotation to an up and down movement.

Have you considered that a wind pump is likely to be useful in almost any situation except where it's needed most........on a very hot, still day?


Gary

gnash, no offence, I'm just trying to work out whether the idea is a starter or not. 17W isn't much to play with. Gary makes a good point - we should look for what energy is most available when air is least available. And that means hot still days. What energy is available on hot, still days?

Savonius rotors, like clothesline rotors, suffer from the basic problem that they are drag based turbines and are limited in a) their efficiency and b) their operating curve. It is probably simpler, more reliable and more efficient to buy or build a small (100W) lift based turbine (propeller) to generate electricity and use that to drive a standard pump with battery and mains backup. A solar panel would help.

Random thought: You can concentrate more light onto a solar panel to get more power, as long as you prevent the panel from overheating (trickle water over it?). Perhaps put the solar panel flat in a tray of water and use some mirrors to add extra light. This heat could be useful in winter for warming the fish.

Here is a nice page on DO vs temp:
http://antoine.frostburg.edu/chem/senes ... g-DO.shtml
Playing around I notice that the maximum DO at 30C is 80% the maximum at 20C, so the limit is more whether we can get the oxygen in fast enough in the first place.

I would consider use using a large diameter fan in the tank to circulate water. I think the oxygen exchange at the surface may be adequate for even heavily stocked tanks, circulation is more critical. A large diameter fan would turn slowly and not be a threat to the fish.

Gary, I did see the rotor that you mentioned and think its a good idea,as with the archimedes screw.
Njh, I,m trying to get away from power completly,(this may sound absurd) but the only time the power goes down here is when there is 1)rain 2)storms.
Both of these weather conditions are mostly carried to Kal via wind.
This is not to say solar would be useless, there is no reason why it would not work.
Better yet why not try to incorporate all the natural sources to get your power/aeration/pumping needs.

AND

ELLKAYBEE, what ever you do in life PLEASE dont stop posting here, I nearly wet myself at your mental pictures

Jaymie, do you have pictures of the bellows and other assorted stuff yet.
would like to have a look see. thanks

I'll have to remember to actually pick the bellows up from the FIL Usually when we leave there I have enough to remember with the kids

Gary- I like the Savonius rotor for simplicity, etc. If your primary purpose is to aereate, Place directly over the tank, and drop a few centimeters. As the wind blows, it will splash around in the water, aereating. If you are using a poly barrel (or better yet, 2 90 degrees apart, you should get reasonable splashing., if you want more efficiency, use g6's slat fan to push the water, and the Savonius stacked. or if you want, use the squirrel-cage fan from an HVAC unit blower, anything that breaks the surface and stirs things up will be a great start. If you start by experimenting, you can find out if you need to run 2 barrels, or if you need to put a centrifugal clutch on that runs a generator/alternator. These could also be scrounged. The biggest problem would be the supporting frame and the axel.

Hummm, could be tilting at windmills here...

but have a couple of old "whirlygigs" in the garage. Similar to one in the pic

Anyone of you wizards out there know a simple way to connect/convert to something in the tank to stir and aerate???

Nearly always a good stiff seabreeze here in summer and good winds during winter

hey gnash,

good to see you think off the grid. i also like the idea of avoiding "power" all together.

keep the ideas coming.

When I worked in Thailand I saw them using 55 gallon drums to make blades to power water pumps.

I also saw a "vertical" windmill made out of one drum.

To connect something like this via a crank (maybe use blue barrells foor the vanes) to either a home-made diaphragm type pump or even a piston type pump (think bicycle pump), has definite possibilities for use as an air pump for pond or tank use.

I unnderstand that some people use car wheel bearings and brake drums as the foundation for mounting the windmill on.

Just needs a few talented people to make it work.

I like the idea of a barrel shaped fan ( like the whirly thing) made out of a blue barrell, and the use of a crank to operate a bike pump.

One prob is some systems have to put a brake on the thing to cope when it gets too windy!

Rupert, we've got an old whirlygig too. The problem with it is that the central shaft goes all the way into the top. You can't easily drill through the top to hang it above the tank.
Our next effort will prolly be like the current fan set-up but with a fan from an air-con unit (8 larger square-shaped blades, stirs the water better than a domestic oscillating fan blade)

The advantage of converting to electricity is that it is easy to handle, store, supplement, measure and control. For a start, you are going to have impedance mismatches between the turbine and the device using it (they will be in the 'wrong gear' wrt each other).

Why are you trying to avoid the grid?

I realised my estimate of 17W is still too big - betz(?) law says that no wind device can be more than 16/27 efficient, so only 10W theoretically available. (Probably more like 1W)

Of course at higher wind speeds you will have more power, but we want this system to operate in minimal wind conditions. The problem is that wind power increases as the cube of the wind speed, so if you get the system working at 1m/s (a common breeze), at 20m/s (gale) you'll have 8000* more power to handle.

You will not get any useful work out of a whirlygig.

Njh,
It's not that we're trying to avoid the grid, as such. More that as with Gnash, when we have a power outage it is usually due to storm activity and so we have heaps of wind. We want to use the wind to aerate the tank when the grid power is down, so that we don't lose any fish to DO deprivation.

I don't know about other members, but we live on a ridge-top and the wind blows here almost all the time. (I want a turbine, I want a turbine...)

It seems only sensible to use a resource we have plenty of.

The little oscillating fan turns quite well in the water, breaking the surface tension and in all likelihood providing additional aeration. It is a simple, cheap insurance for our fish.

then I claim it would be more efficient and reliable to generate electricity and use that to run all your current systems, rather than building a complete separate system only used in a storm. It is always better to separate distinct problems and solve them as well as possible, separately.

You can't break surface tension mechanically. Indeed, you can't really break it at all - it's a property of water.

When I get the time (and possibly the neighbors washingline ) I will have a go at building something and run tests.
Have found a heap of blue barrels where the missus works,they have been used to store hydrochloric acid and I`m not sure about using them for growbeds, so I`ll cut them up and use them for wind catchers.