Aquaponics - Yabby farming

I'd really like to be able to grow yabbies for the plate, but they are a little too cannibalistic and need a lot of space.

After a lot of running stuff through the invention engine, I came up with an invention to save people who have fallen through ice.

But that's another story.

The stuff that came out on crustacean farming was a lot more interesting because I don't have the falling through ice thing to worry about where I live, and like eating yabbies.

I think I'll patent the ice thing after a little development.

In the mean time I think there's a way to grow a lot more yabbies in a lot less space.

In the past I mentioned a few ways this might be achievable based on some observations, and one was that if food came to the yabby, it would sit in it's hole all day and wait.

A yabby waiting in it's hole all day hardly ever eats another yabby also waiting in it's hole. The result is yabby utopia.

They would be free to move around if they felt like it, but wouldn't do quite so much of it.

Much more like cows in a rich pasture full of 20cm high green grass rather than a hen in a 30cm cube cage.

Or at least that's what I think.

So here's what you do...

You create a shallow tank that holds PVC tubes slightly longer than the crustacean and wide enough so that they feel safe and perhaps set at 45 degrees or vertical, or whatever it turns out yabbies like.

Not too wide. 12mm black poly pipe for new borns, 18mm black poly for when they are around 2cm-6cm, then thin PVC until maturity would be a guess. Actually thicker poly irrigation would probably cost less.

You set them in a gravel/scoria/clay ball media making sure there is a few feet thick of the stuff under the PVC tubes.

The more tubes you want to set per square area, the more depth of media you need. 500L of media can support around 12kg of life. (depending on how much you feed it)

Put something under the media or run a stack of PVC pipes with slots cut in them so you can collect water from all over the bottom.

Add a pump to collect water from the bottom. An air lift would be better because it's a zero head lift and they run at a tiny percentage of the cost of a water pump.

Next you add enough water so that your tubes are covered by only about 4cm of water, plus half the length of your crustaceans at the stage of life they happen to be. Adjust as required, but this can be pretty vague.

You fill the tank with duckweed and pump so it draws water from the bottom of the media and expels it above the media pointed in such a direction as to set up a gentle movement all through the tank.

A round tank would probably be best, but square would work.

Add yabbies.

The yabbies sit in their holes.

The duckweed's 3-4cm roots float past.

The yabby grabs one, pulls it down and eats it.

The yabby grows. And excretes stuff that is either ammonia, or becomes ammonia.

I eat the yabby.

Duckweed can eat ammonia directly which is probably why it can choke rivers and lakes so brilliantly.

Duckweed has crazy mad Fu.

Most plants require bacteria to turn the ammonia into nitrites, then another bacteria to turn the nitrites into nitrates which the plants then consume.

When a plant can eat ammonia, it will always get first crack at the available nutrient. It also floats so it causes a blanket of shade at all the plants that live underwater. So duckweed gets the double advantage of all the sunlight, and all the nutrient.

The tank would definitely need a glass lid because yabbies love to escape, and a glasshouse would make both the yabbies and the duckweed grow well.

You would need to supplement the nutrient by adding duckweed from another source if you had a lot of yabbies, or adding some peas or brussels sprouts or something. Yabbies eat everything.


That's it.

I'm pretty sure it will work.

Thinking - wasabii

note to self. when you lost one lens of your glasses and you put a tissue over the lensless bit so you could see ans then you ate food with wasabi and then you used a tissue as a napkin they are not interchangable

throw all tissues away under such circumstances

eBike - Electric bike lights

Mrs 120ThingsIn20Years pulled up in her eBike only to grab a hand rail and detach a bit of tendon that should have never been detached.


She's under the Plastic & Re-constructive Surgeon's knives, scanners, and other bits of kit as I type. So this is part blog post, part self distraction.

We are so lucky in the west to have access to all these amazing experts who learnt all this amazing stuff from all our amazing universities, then went on to work at places with amazing tech that can do amazing things.

Head transplants and so forth.

Sometimes medical staff (oneofmyformerelderlyGPs) forget they didn't get there on there own, but rather because we wanted them to be put there so found the cash to teach them, and that perhaps the poor people in the hospital where they used to work were poor because they were sick or something, and not just because they loved daytime television.

But more often than not they are an awesome bunch of people.

So thanks medical type people everywhere. If it wasn't for you, I would have been dead ages ago, many times over.


Tail lights and indicators had nothing to do with this mishap, but I cant help feeling it might be nice to not have to take your hand off the front brake (right hand) to signal a right turn across traffic (we drive on the left). If you don't signal you run the risk of getting killed, and if you do, you will almost certainly be killed.

Especially by that loony driver who was driving on a moonless night with their lights off. Thanks loony driver for near missing me. A near miss is always better than a light graze.

Anyway, I thought I'd make some indicators and brake lights and things.

I figured I'd use a PICAXE programmable chip to make everything work.

I further figured the feature list should be ...

  • Headlight control so I can set strobe, always on, hi/low beam or whatever. This way I can add my own light directly to the eBike power supply at some stage, and turn the world into daylight if needs be. When we are on the road, a strobe headlight is always a good thing so you don't get lost amongst all the other white lights. But we have a lot of cycle tracks in Adelaide Australia, and when you're on the tracks, being able to see is more important, so you want solid bright light.
  • Turn indicators with a handlebar mounted three way thumb switch with off in the centre, and some kind of beeping sound that reminds you that they are on. Maybe a auto cancel function after 30 seconds (with an extra beep to let you know or something).
  • A brake light that does something dramatic to draw attention to itself, and when it's not being used as a brake light, should just go about acting like a normal tail light.
I think it's important to have a solid red light (most bike tail lights here strobe) to give the indicators a point of reference. It's will be difficult for a driver to tell if your indicator is the left or right without a red light reference point I think. 

For the brake light drama, I'm thinking along the lines of a rapidly increasing strobe that flashes faster and faster, then settles on solid bright red light. The flashing stage would take perhaps one second and should continue even after you take your hand off the brake, so you can use it as a "HERE I AM, LOOK AT ME" kind of thing. Just touch the brake when you think people need to be reminded of your being made of soft squishy stuff that goes all rancid when all your blood falls out, and then you can get back to escaping from them.

Then one last feature should be a "strobe everything" function in case of emergency. I might also attach that to the warning device.

My current warning device is a bell, but it's soon to be upgraded to a container ship's fog horn, and a baseball bat with a nail through the end of it.

Actually I think I might start a campaign that says a green flashing light on the end of a flexible fibre glass rod that extends two feet into traffic means that there is a diamond on the tip of the rod ready to gently (without disturbing me in the least) draw a line down the length of your car's paint if you get too close.

120 Things in 20 years thinks that the emergency "strobe everything" function would be best voice activated by a scream.

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