Aquaponics - Colander feeder

One of the requirements for a SLO (solids lifting overflow) is that you need to concentrate the fish solids with a whirl pool.

One of the issues with making a whirl pool in my fish tank is that it's a cube.

I found by pointing the powerhead, I can make the solids collect where I want, but the result is that any feed I put in tends to be removed as soon as it hits the bottom before the fish get at it.

I figured I needed something to hold the food off the bottom until the fish eat it, so I made use of a large kitchen colander.

I hung it by three strings, and then tied an extra string in a loose loop around the three.

That's the three strings going off to the right, and the loose loop going off to the left.

The result is I can pull the thing up to the surface and to the side by pulling on the loose loop to add the feed.

Then I can just let the thing go to slowly drift back to the centre, where it remains suspended a few inches off the bottom.

I found that anything sitting on the bottom was collecting solids so I keep it high enough to allow a free flow under and around it.

The result is any solids can go straight into the SLO and to the grow bed, but any food hangs around until it's eaten.



The other result is that it's driving my fish crazy as they can smell the food, but haven't quite got the hang of going over the top rather than trying to eat it through the holes in the strainer.





My new 120 things in 20 years, Aquaponics - Colander feeder fish frustrating catch cry is "They'll figure it out".

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 - 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 - The state of the fishies

Happy birthday 120 things in 20 years!

I was looking through my youtube videos and was quite surprised to see how much my fish had grown. I forgot how small they were when I first got them.

They now look like this. The largest is probably around 22 cm long. The water temperature is only 10 degrees c in the morning because of overnight heat loss, (it's winter in this part of the world) but I'm running a powerhead (a powerhead is a fishtank water moving device that acts more like an outboard motor than a pump) to keep the water moving. This seems to be making them more active, and they are eating much more than I would expect.

Normally silver perch shut down at around 16 degrees c and eat only a tiny amount until water temperatures improve.

They seem to love the high flow rate and actively seek it out, even though there are calm areas in the fish tank.  The following video is in 10 degree c water.

They used to look like this!

Aquaponics - Silver perch underwater

A front loading washing machine makes fish more visible.

I salvaged the door from a broken front loading washing machine, and suspended it over my fish with the camera sitting inside it. Camera washing machine goggles allow me to see my silver perch underwater. After seeing the results and being able to see the underwater component of my aquaponics test system, I'll definitely be incorporating some kind of porthole into the lager system.

I turned on the powerhead, and pointed the camera where the current was strongest. The fish seemed to love the strong current and spent much of their time in the full strength, rather than taking cover behind the pump at the other end of the tank where it was relatively calm.



While I had the camera outside I thought I'd try to measure my fish. I dropped a 10 cm length of plastic pipe into the fish tank so as to get some idea of their growth rates. And after photographing the school next to the pipe, was surprised to find I actually had eleven. I thought I had nine.

The smallest is still only around 7.5cm and the largest is around 15cm.

I think they might have been much larger if not for the stress they were put under from the poison plant, and the fact that whenever I lost a fish, I would stop feeding them for a day or two, then feed them only a little for the next week. It's standard practice to stop feeding the fish when anything goes wrong in your aquaponics system to ensure there is no extra pressure put on the fish from nitrite or ammonia spikes. Often a fish death can increase your levels of ammonia and nitrite to dangerous levels, so feeding the fish can just add to your woes. It doesn't harm the fish, and potentially can be of great benefit.

Aquaponics - Inverter based electrical backup system

We get a lot of blackouts.

Fish hate blackouts.

I'm going to blackout proof my planned, larger, aquaponics system by building an electrical backup. I also need to build my planned, larger, aquaponics system.

Here's what I've done so far...

Attractive isn't it.

I happen to own a one hundred amp hour deep cycle battery. That's it in the bottom right corner of the picture.

I also own a multi-meter, a battery charger, a powerhead, and a bucket of water. 

As of today I also, also own a 200 watt inverter. It's a device that turns 12 volt battery power, into mains power. I had to buy it. A small inverter doesn't cost much and you can pick one up online, or in camping sections of department stores.

A power head is essentially a fish tank stirrer. It aids in supplying the water with oxygen, and will also create a bit of a whirlpool to concentrate fish waste solids into the center of the planned, larger, fish tank. This will allow the solids to be extracted from the fish tank, and moved to the planned grow bed where they belong. 

The powerhead is a critical component, because I'll be relying on it to supply oxygen to my fish in case of a power outage or pump failure. That's the powerhead in the blue bucket. It's basically just a small motor with a propeller on it. According to the box it came in, it moves 5000 litres of water per hour. The best part is, it moves all that water with only a 12 watt motor. My pump also moves about 5000 litres of water, but it has a 150 watt motor. 

The pump's main purpose in life is to supply the grow bed with nutrient rich water, but the bacteria will be fine for a couple of days if it fails. A system full of fish on the other hand, will start to suffer within an hour or so if the water isn't moved around.

I'll run the pump on a timer, so that it runs for around 10 minutes of every hour. I'll run the power head all the time.

The plan is to run the powerhead from the large battery, via the inverter, and to run a battery charger to keep the battery topped up at all times. Based on the tests I'm currently running, and on my rough calculations, in the event of a blackout, I estimate the battery should last approximately forever. 

So far I've been running the powerhead for 4 hours using the battery alone (ie without the charger), and the batteries capacity has actually increased. Which is odd. I'm guessing it has something to do with the day warming up, which might be changing the battery's abilities. 

This electricity stuff is really the kind of thing I should know something about. Perhaps I'll look into it.

Aquaponics - Exclusion zone

It's said that a picture paints a thousand words. But I'm confident that I could have described this in under two hundred words.

I had another silver perch commit sashimi yesterday. I'm not certain if it was due to being caught up in the original ruckus, a new ruckus, or some mystery problem that I'm yet to discover.

I built a new and hopefully improved exclusion zone around the pump made of a soft drink bottle with some holes drilled in it. There. That took only ten words. They are already trying to defeat my new anti-fish security system as I type.

I get the feeling they are desperate for cover as they seem to be trying to burrow behind and under everything they can.  No doubt they are distressed at all my mucking about in there. Tomorrow I'll add a terracotta pot or something suitably non-toxic as something to hide in or under. I think they have had enough for today as I'v had my hands in their world for the last hour or so trying to block all the entry points to the pump.

This episode has raised some issues with regards my design for the bigger second system. I'll need to figure out some way to make the powerhead safe.

I also discovered as a result of a head count that I actually took delivery of twenty two silver perch, not twenty.

Aquaponics - New pump and powerhead

My old pump looks like this. Yes those opposing wire loops I added are in fact the new front bearing. This is the pump thats been running for the last 45 days in the small blue barrel test system.

I took delivery of the new pump and powerhead. This is for the second, larger aquaponics system. The pump is the big box and the powerhead is the small ball shaped thing on the top left.

The pump will shift 5000 litres per hour at zero head. That is to say if all you were using it for as a stirrer it would shift 5000 lph but if you want it to move water uphill, the amount of water it can move tapers off depending on how high you are trying to move it.

For some crazy reason not all pumps tell you how much they can pump at any given height. This one only tells you that it can pump to a maximum head of 5 metres. That means you will get 1 drop per hour at 5 metres . From what I'v read and seen, at 2.5 metres you can expect a bit less than half of its maximum output. So I'm hoping this one will pump around 2500 litres per hour at 2 meters head. It might turn out to be a bit more than 2 metres so I made sure there was plenty of excess. I hope. All I need is 1000 litres per hour so It shouldnt matter.

The pump is 150 watts but will only run for a few minutes every hour. The powerhead on the other hand will run all the time in the fish tank, but is only 12 watts even though it also moves 5000 litres per hour. The powerhead cant lift water at all and is there only for its ability to stir water to aid oxygenation. The powerhead's other function is to create a slight whirl pool which will make solid fish waste gravitate to the center. Once there it will be picked up by the overflow outlet. and piped to the pre-filter.

Aquaponics - Overflow pipes

One small but very important detail I left out of the SketchUp diagram in the previous post is overflow pipes. If something goes wrong with the system and the siphons fail because a potato or a snail has made a home in one, it is vital that the water has some way to get back into the sump. The pump in the sump will be damaged if it is run without water.

Overflow pipes are simply pipes that will drain the grow beds before they overflow onto the ground. The pipes are set slightly above where the siphon would normally trigger and run through the side of the grow bed and back to the sump. If for some reason either of the siphons should fail, the water will run back into the sump and keep the system running. It wont be ideal but the fish will be happy and the pump will be happy. The plants should be fine as long as the beds don't stay flooded for too long.

They should never be needed but for the sake of $5 worth of fittings its worth adding them.

For an additional few cents a very small hose can be connected from a hole in the bottom of each grow bed to the overflow pipes so that there is always a small constant stream of water draining from the grow beds to the sump. This is done in case the main pump fails. In the event of the main pump failing, the garden beds could be half full of water and the plants can suffer as a result. The slight leak allows the beds to drain albeit over a few hours.

Main pump fails -
grow beds slowly drain and will be fine for up to 3 days (plants and bacteria) depending on weather.
fish are fine because the powerhead keeps the oxygen levels up.

Power head fails -
doesn't bother the fish as the main pump is still doing it's thing.
doesn't bother the grow beds as they don't get any water from the power head.

Siphon fails -
water overflows through the overflow pipes back into the sump so sump pump is fine.
gardens are flooded but they can take that for a while depending on the plants (eg. lettuce can grow in permanently flooded beds)

Within an aquaponics system its always good to have backups for whatever critical systems you have, especially when they can be done for a relatively small cost.

Aquaponics - CHIFT PIST

You see CHIFT PIST a lot in the aquaponics forums and it means "constant height in fish tank, pump in sump tank". And its a very good idea. This is a Google SketchUp design of how I plan to implement it.

In a CHIFT PIST system the main pump is pumping clear filtered water with no fish waste solids in it so your pump will last longer and wont ever get blocked.
The pump pumps water up to the fish tank and the fish tank overflows into the grow beds.
In this system we will have a second pump running from a battery because we get quite a few blackouts here. Fish don't like blackouts. The second pump is not really a pump but more like a propeller, so it wont get blocked by solids. This propeller thing is called a power head, and its purpose is just to stir the water to oxygenate it. The main pump in the sump is a proper pump in that it can push water up hill through a pipe, but solids will block it.

The advantages of a CHIFT PIST aquaponics system are ...

- the fish tank has no holes in it other than an overflow pipe but that is right at the very top. It also has no pump in it so not a lot can go wrong with it. The water level is always right at the top so the fish are happy.
- the pump is in the sump where the water is clean and filtered free of fish solids.
- there is extra water in the sump giving the system more stability. If the plants don't use all the nutrient for a while, it has less overall effect on the system because any negatives are diluted by the extra water. The sump acts as a buffer against any extremes in water condition, and gives the system a little extra time to sort itself out.

Because my SketchUp skills are lacking, some aspects of the system are not pictured. I'll get back to those in later posts. SketchUp is a 3d drawing program that Google offers. It's free to download and very easy to learn. You can get it here if you want to have a look.