Aquaponics - Easy automatic duckweed feeder

Sorry folks, just a quick proof of ID.

Hi BYAP.

Actually I do have something to post though.

I had another idea for an automatic duckweed dispenser, and it works!

The previous one looked like this...

Or this from the side...

In this new easy one, all you need to do is pump some water into a pond a that's a bit higher than your fish tank, then create a flat spillway that falls into your fish tank. Make the spillway quite broad so the outflow is slow (or have a low flow to the duckweed growing tank). The idea is to not have the duckweed all flow out. A good way to do this is to create some texture on the flat spillway. paint on some silicon mixed with some fine gravel or something. 

It's a good idea to add water to the duckweed pond so that the water swirls. This way the duckweed builds up in the middle, and less will flow out at each time it triggers.

If the flow and texture is correct, the duckweed wont flow over because it gets a bit stuck on the spillway. 

After a while, the duckweed grows thick enough that it blocks some of the water. In my little decorative system, I get a rise in tide of around six or seven millimeters before the pressure builds up enough and dumps about ten percent of the duckweed into the fish tank. 

It wont dump again until the duckweed has grown back.

The result of this is that you never run out of duckweed, you feed more duckweed in the summer (when duckweed is growing faster, and your fish want more food) and it's automatic.

Not a lot of posts for ages. but I'm still doing stuff. 

Aquaponics - Direct composter success

I just got back from my trip to the East coast of Australia, and was happy to find the system ticking along nicely.

Some of the dried duckweed in my direct composter looks like it might be trying to live again, but I cant tell if it's greening due to life or mould.

There must have been some heavy rain while I was away, as it was soaked through.

I think I'd better put a lid on it.

When I lifted it up I saw a stack of worms going to ground into the growbed, and some more hanging from the little composter.

The worms seem to like it.

It was also very easy to grab a handful of worms for the fish, so the fish seems to like it as well.

It should also be adding some nutrient back into the system, and also saving some because of the duckweed I removed, so the plant will like it as well.


All in all, I count this a complete success, and it seems like quite a good solution to my problem of only having one fish.



120 Things in 20 years thinks flying around in helicopters is a pretty good way to spend some time.

Aquaponics - Duckweed - direct composter

Having dried some duckweed by spreading it out on some concrete for a few days, the next stage in creating my direct composter is using my cheese press to bring it all together. My PVC cheese press has seen a few different purposes in it's lifetime, but this one looks like it might be the one it retires to.

The duckweed shrunk down to a quarter of it's former live self.

I found my PVC pipe with holes that was formerly a cheese press, and rinsed it thoroughly.

I filled it with the dry duckweed, and planted it into the growbed.











The day after tomorrow, I'm off on an adventure to the other side of the continent, but tomorrow, which is really the day after tomorrow a far as this experiment goes, I'll check to see if the worms like their new feeder. But really I'll be somewhere else.




120 Things in 20 years is wondering if anyone is actually following this convoluted narrative.







120 Things in 20 years thinks that as far as it can tell, it's made a worm motel.

Aquaponics - Direct composter - duckweed drying

My system has only one fish, and I'm getting a little worried about my growbed's worm population. I'm not confident there's enough fish waste going into the system to feed them all.

What I thought I might try is creating a small compost bin directly in my growbed to make sure the worms have enough to eat.

I have a lot of duckweed growing in my system, and that one fish has to power the new bigger growbed, and the duckweed.

Duckweed uses quite a bit of useful nutrient so I thought I should remove some, and add it back into the system via the composter.

 I pulled out a quarter of a bucket or so of my duckweed from the system, and dumped it on some dry, sheltered concrete to dry.










I need to dry it first to kill it, because the direct composter will be a small container full of holes, sitting directly in my growbed. That means it will be damp, and the duckweed might just stay alive.

As I understand it, worms feed on the stuff that feeds on rotting vegetation so live duckweed wouldn't work so well.


120 Things in 20 years seems to be growing plants for feed to grow other plants. I think I finally developed a way to make growing vegetables as inefficient as growing beef.

Aquaponics - Duckweed

Since I moved my duckweed into it's new home it's growing like some kind of thing that grows a lot.

It looked like this nineteen days ago.

Then eighteen days ago I lost a lot of it because I overflowed my tank and all the duckweed went for a walk over the edge.

It looks like this today.

It's not lost on me that this is a poor comparison.

I realise they look pretty much the same, but this latest one is many layers thick in most parts. The original pic is all a single layer thick. I had no idea it could grow this way in multiple layers.





I suspect this is a dangerous thing to grow on top of a fishtank as it might choke the water. I doubt  the water will see enough oxygen. If not for the fact that I only have one fish, I think there could be trouble.

I think I might scoop all this out and do a time lapse of it growing back, but then I think I might move it into some other containers or something.


120 Things in 20 years wants some trout fingerlings.

Aquaponics - auto top-up water

I've had an idea.

I had my duckweed tank connected to my fish tank via a no holes siphon (a tube full of water with en end submerged in each container). This saved the day when I had a spill from my strawberry tower.

The level in the fish tank and the level in the duckweed are always kept exactly the same, so if I add water to the duckweed tank, it flows into the fish tank, until equilibrium is reached. This means the duckweed tank breathes in and out with the fish tank.

That all works well, but I would prefer to have the duckweed tank full, to add extra thermal mass to the grow house and keep temperatures more stable.

So what I thought I'd do is make a flexible hose from the bottom the duckweed tank go over to the fish tank, but instead of submerging the end, I'll add a float, and a vertical pipe. If I cut the pipe at the same height as the duckweed tank water level when the float is floating in a full fish tank, I think water should flow from the duckweed tank into the fish tank if the water of the fish tank gets too low.

I think.

Or something.

Definitely something interesting or not should happen.

I'll try it.

If it works I'll explain it better.

Aquaponics - Self cleaning swirl filter Mk 2

I think I have a better idea for a self cleaning swirl filter.

Water enters a bucket part way up from the bottom. My picture show half way up, but I think it would be better where the "*" is around a third of the way up. The water enters via an elbow to set up a whirl pool.

Solids gravitate towards the centre, and sink to the bottom.

The first dump back to the grow beds is a hole in the stand pipe down the bottom, that creates a constant, gentle, downwards flow to further encourage solids to drop out of suspension.

The second dump device, is a bell siphon that periodically dumps water, creating a powerful suction, cleaning the filter of collected solids and returning them to the grow bed. This siphon is shortened by a breather pipe that means it only changes the height of water from between the "high tide" and the "low tide" marks rather than dumping all the water. If all the water is dumped, you loose the gentle entry of the water, and the swirl is broken down each time the device is empty.

A third dump intermittently exists at the top of the filter to act as a leaf skimmer. This would only flow at the top of each fill cycle, and would just be a trickle for a few seconds as the container is at its fullest, and would dump any floating particulates back to the grow bed.

Finally, water exits from the filter from a point just under the low tide mark. This would be the water that flows through the NFT tubes as it would be almost free of heavy solids, and would also not collect any floating solids.

Floating solids are sometimes sucked into the pump when fish disrupt them from the surface, when they get caught into a whirl pool and sucked down into the pump, or when the grow bed empties onto them, pushing them under water. Duckweed is at a very fine balance between floating and sinking when it's getting old, and can stay under water for a minute or so before slowly rising back to the surface. A fish swimming by can easily pull some under water where it might find it's way to the filter. It doesn't happen often, but I find 3 or four leaves a day go through the pump if I put a sieve under the grow bed outlet to check what the pump is lifting up.

There you have it, a self cleaning swirl filter.

Perhaps.

I'll make one to check.

Aquaponics - No holes siphon

A no holes siphon has no holes.

It also allows you to make the fluid level in two containers the same height in each, without having to drill holes in them to join them with a hose.

In it's simplest form, it's a hose full of water with both ends kept submerged, one end in each container.

As the level increases in one container, water siphons into the other. As long as the tube remains full of water, the two levels stay the same.






This can be a very handy solution to adding an extra fish tank or grow bed without having to empty your originals.

I used one to share the water between my duckweed tank, and my fish tank. As the level in the fish tank changes due to where it is in it's cycle of pumping water to the grow bed, the water flows in and out of the duckweed tank maintaining the two containers at the same depth.

My duckweed seems to love the fish tank water. In the past I have kept it separate from the rest of the system, but now it's moved into the glasshouse.










There are a few ways you can implement it, but the simplest is to submerge a tube in water, then block both ends with your thumbs.

Take one end and submerge it into one tank, and the other end in the other tank.

When you remove your thumbs, the tube remains full of water, and a siphon starts to equalise the two containers until their surfaces are at the same height. If one container is at a different height, the water will try to settle so that the surfaces are the same height, so if there is too much difference, one container might overflow.

Make sure there are no air bubbles in the pipe, as they will break the siphon, and the exchange of water between the two containers will no longer occur.

Another way to make one would be to submerge the ends of the pipe, one end in each container, then connect your pump until water is flowing freely. Disconnect the pump, making sure you dont lift either end out of the water, and the tube should remain full of water.

Aquaponics - Duckweed growth rate

I hadn't noticed my duckweed growing, because I tend not to notice such things. But when you compare two photos taken a week apart, it becomes difficult for even the most stubborn unobserver to ignore.

Duckweed grows really fast.

This is what it looked like on the day I bought it.

And this is what it looked like a week later. And I'd given some to the fish!

I only noticed it a few days ago when I was sorting photos.

It does grow only in two dimensions, but it is still amazing.





Duckweed is known for choking river systems, but it's only because the water is far too nutrient rich from fertilizer runoff and other intensive farming and industry. The single leaf with the insect on it still looks the same after a week. I was expecting to be able to show it dividing, but its growth is slow, probably because the water it's in isn't saturated with nutrient.

It's interesting to note the small root system the photo at the top of this post shows. I couldn't see those roots without the aid of the camera. I thought each leaf had a larger white root, but it looks like there are many on each section that will one day become a plant on its own, although its possible that those fine green roots are actually algae or some other type of bio string.

Aquaponics - Duckweed auto feeder side view

To add clarity to the previous post, here is a side view animation of the duckweed auto feeder.

Aquaponics - Duckweed auto feeder

I've had an idea.

Duckweed grows at an amazing rate. It also seems to spread out to take up the entire surface available to it. This appears to be a function of surface tension. But I may well be wrong so don't quote me on that. In fact, don't quote me on anything.

Because of the way duckweed spreads out over it's available surface, it should be possible to use that, and various other handy attributes of the universe, to make an Aquaponics duckweed auto feeder.

Here's what the original plan looked like.

The pump for my new aquaponics system will be on a timer, and will run for around 10-15 minutes each hour. When it runs, a small amount could be diverted to the duckweed auto feeder. The diverted stream could be applied to a PVC pipe  in such a way as to divide the floating duckweed. If required, the stream could be shaped so it spreads across the width of the PVC, and perhaps points away from the standpipe. If the stream is set to spray across the top of the water, it will keep the majority of the duckweed away from the standpipe, but still allow the water to pass under the stream,through the standpipe and into the fish tank.

Here's the animation that might make it understandable.

Aquaponics - top down view of duckweed auto feeder 

• When the water flows in from the sump pump, a small amount of duckweed is separated from the majority, so that it moves toward the standpipe (to the left) and the rest is kept away to the right.
• The water overflows into the standpipe, into the fish tank.
• The overflowing water takes a "dose" of duckweed with it to feed the fish.
• The size of the dose can be determined by the placement of the water inflow. Moving the inflow further to the right would increase the duckweed dose, to left would decrease it.
• Because the duckweed spreads out to occupy the available space, the dose would be a percentage of what remained rather than a set amount. This means you should never run out of duckweed. If there isn't very much in the system, only a small amount would be delivered.
• The duckweed will grow faster in summer when the silver perch want more feed, and it will grow slower in winter when the fish are not so hungry. The faster it grows the more the system will deliver on each pump cycle.
• If required, a thinner PVC pipe would allow for better fine tuning to allow a smaller amount of duckweed to be delivered each time.

Once it's set up, it should largely regulate itself.

My plan is to make a large bed of water to grow duck weed in, using goat dung for nutrient, and create a duckweed auto feeder connected to my fish tank, that I can scoop some duckweed into every few weeks.

Here's a side view animation 

Aquaponics - Duckweed

Duckweed!

I finally got hold of some. I've been looking around for it for ages, but all the plant stores stock a plant that isn't really duckweed. Every single nursery I've been to has assured me over the phone that they stock the real deal, but have all turned out to have something else.

I guess I should mention that the reason I wanted the stuff is because fish eat it. Its a great way to get rid of excess nutrient, and is also a useful feed because it floats so doesn't get sucked into the pump before the fish get a chance to eat it.

It looks like this. At least I hope it does. All plants look the same to me.

Duckweed has some claim to fame. I'm told it produces the smallest flower. But I wasn't told it makes three of them, so I guess there is good reason to doubt it's record holding status as well.

Who knows.

I have duckweed.


As far as I can tell duckweed normally reproduces asexually by dividing into two leaves. If you look at the picture, you can see some leaves almost look ready to divide. Many of the leaves have two roots extending ten or fifteen millimetres into the water. I'm guessing when the leaf decides into two, each half gets a root. I'm told that it also does the pollination thing from time to time, but who knows.

I have duckweed!

I put some into a large container with some fish emulsion as fertilizer. After a day or two I noticed an oil slick, so I  added an air stone attached to a small fish tank air pump. The slick cleared up within a few hours, and the duckweed took on a healthier shade of bright green. I know there isn't a lot of science in that, but I'm guessing duckweed needs oxygenated water. I was hoping to just keep it in a container of water with a large surface area, throw in some goat dung, and leave it to it's own devices, but I don't think it's going to be as simple as that.

The plan is to use the original planned growbed with pvc edge capping for a duckweed plantation. The growbed was too easily scratched to use with gravel in it, but filled with only water and duckweed, it should be fine.



I kept it for five days before giving it to them because I was concerned the pond it came from could have had some diseased or parasite infested fish.

I only know a small amount about one fish ailment other than poison plants, and that is a parasite called Ich. Ich is a fish parasite that can't live away from fish for more than three days, so at least my five days should prevent it from being an issue.