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.

Aquaponics - Rainwater tanks

I managed to get some rainwater tank freebies from friends doing some back garden renovations.
The plan for my new aquaponics system is to turn one of them into a pair of grow beds, and the other into a sump tank.

The rainwater tanks measure approximately 1100mm by 1750mm by 600mm. This should allow me to split  one along the seam as garden beds and use the other as a sump tank. More on sump tanks later.

One tank split into two grow beds allows a perfect size to work with. Garden beds should be around 300 mm deep as the bacteria and plants both enjoy this depth. I will have two beds measuring 300mm deep and 1100mm x 1750mm in area. This is great because the longest my arms will need to be is just over half a meter in order to reach all of the grow beds with ease. I have arm to spare.

This is the site I'm working with. It is almost flat and is edged by a slope which will work perfectly.

Watch this space!

Aquaponics - Plants

Most plants love the environment provided by an aquaponics garden. Fast growing green leafy ones love it even more than everything else because there is always as much water and nutrient as the plants need.

Spinach (baby spinach pictured here), lettuce, basil etc will all grow amazingly fast in an aquaponics system. From what I'm told, the only plants that are probably not worth planting in aquaponics are ...

- mint, because it goes crazy and will take over the planet given half a chance.
-root crops like potatoes,  because it seems potatoes think its funny to make little ones in your siphon standpipe and everywhere else you don't want one. They block all your pipes and cause a stack of problems.
-beans. There are conflicting reports about beans. It seems beans don't like immature systems but grow just fine in systems that are a couple of years old.

One very important thing to keep in mind is just how much produce you are going to get from each plant. Don't plant out a half a dozen of anything that bears multiple fruit (like zucchini) unless you are in a family of ten or are planing on setting up a roadside stall. I've heard reports of well over a hundred cucumbers from a single plant and insane numbers of tomatoes.

Remember to plant things like lettuce every week or so to ensure a constant supply. You can just sprinkle seeds around and they will pop up some time later when you disturb the grow media. As you harvest a lettuce another will take its share of the light and grow like mad!

You can grow things very closely together because there is always plenty of nutrient and water. The plants don't need to compete for stuff that plants like so they all get along just fine. So plant them as close together as you can, allowing for just enough space to grow to full size.

Aquaponics - Bell siphon

The bell siphon was a clever thing for someone to design, and as such you feel a bit of that "clever" rub off onto you when you make one. I made one, and feel a slight increase in my cleverness.

There isn't that much to a bell siphon, but what little there is tends to be very important.

A bell siphon consists of ...

- a standpipe (the bit that goes through the bottom of your grow bed)
- a bell (the bit that sits over the standpipe)

A bell siphon can also have...

- a siphon breaking air tube
- water inlet holes
- a media screen (cut off soft drink bottle with holes)

The bell sits over the standpipe.
The siphon breaking air tube is a tube that goes from the uppermost chamber formed by the bell, to a point around 1.5 cm above the bottom of the grow bed. If you dont have the tube, its possible for the siphon to continue draining the grow bed as the water is being pumped in. That is, when the siphon should have stopped and the bed should be filling again, it is possible that water will just keep flowing out at the same speed that its flowing in. By allowing a small stream of air into the top chamber you can break the siphons ability to continue suction when the water gets low enough to expose the pipe. When the bed is full and the siphon starts, this tube doesn't really do anything because its sucking water not air.  But as soon as the bottom of this tube is exposed to air, it brings the siphon action to an abrupt halt allowing the cycle to start again.

A bell siphon also has some cutouts to allow the water to flow in unrestricted. These can be cut outs or a series of holes drilled near the base.I used cutouts.

Make the standpipe not too tall (so water doesnt get blocked by the bell sitting right on top of it) and also wide enough to allow enough water to drain through it. The standpipe needs to have a diameter large enough to allow the water to drain faster than the pump is pumping water in. A large diameter standpipe is important, but dont go too large. If the standpipe is too wide the water will be able to run down on only one side and never form the seal required to start the siphon. If this happens the water will just flow out at the same rate the pump is pumping it in. To get the siphon to start, reduce the size of the standpipe or increase the flow rate of the pump until it's flow fills the tube.

Some things that will cause your bell siphon to fail are...

- air bubbles in the hose running back to your fish tank. (keep it free of kinks and always sloping down - the return hose should drain until it is completely empty at the end of each cycle)
- too small a diameter of standpipe for the flow (or too much pump flow)
- too large a diameter of standpipe(or not enough pump flow)
- gravel getting into your siphon (make a media screen)
- water entering your standpipe too much from one side (cut your standpipe so that its level to help get a rush of water all at once when the water level gets high enough - this helps fill the tube and start the siphon)
- having too small a gap at the top between your standpipe and the bell (make your bell taller)
- restricting the flow within the bell because there is not enough gap for water to travel up the bell (make your bell wider)

Even though aquaponics is a fascinating subject, when you make a bell auto-siphon those around you will tire of your company quickly. Try to include other topics of conversation when meeting friends. Other people wont find your auto-siphon as interesting to watch as you will.

[link from the future on calibrating a new bell siphon]

Aquaponics - Grow beds

On day 4 I made life! Pictured is a coz lettuce 4 days after the seeds were sprinkled around.

When you first start running your system you do it without fish because the environment is too unstable. You can do it with fish but have to be very careful to avoid a stinking mess and some major karmic debt.

I'm happy to eat fish (and can cope with any fish deaths that may occur as a result of my eating them) but don't trust my new abilities as a fish farmer, so I'll be doing what is called fish-less cycling to get my system started. That doesn't mean you can't put plants in because, it turns out,  to cycle fish-lessly you add ammonia in some other form, and the entire process works just fine without the fish.. I'll talk a bit more about fish-less cycling in another post.

 A garden bed or grow bed (abbreviated in online forums as GB) is filled with some kind of gravel-like media so the plants have something to hold onto, and so the nitrifying bacteria have somewhere nice to set up house.

It seems plants don't actually like the exhaust that fish put out, but bacteria exist that love to convert it into stuff other bacteria like to convert into the kind of thing plants like.

Fish excrete ammonia, (fish don't like ammonia) some bacteria change that into nitrites (fish don't like nitrites either) and then some other bacteria convert nitrites into nitrates. Plants seem to like nitrates and fish don't hate nitrates quite as much as they hate all that other stuff. This process is known as the nitrogen cycle, and more information can be found here by clicking this.

The gravel that you use depends on how wealthy you are. You can buy clay balls that look nice, are great to work with, and work very well. Or, as I have you can use scoria (some kind of volcanic rock with lots of holes in it). you can also use gravel.

I used scoria (and a small amount of an experimental clay based media I made) because it cuts your hands and is difficult to work with. I'm not very wealthy. It was cheaper and it has a stack of trace elements that should make themselves available to the plants over time. My scoria is also red, most red stuff in rocks in Australia (I'm in Australia) is iron. Plants like iron. Scoria also has a huge surface area because of all the holes and because of its irregular shape, so there should be plenty of space for the bacteria to colonize and lots of cavities to hold water.

scoria looks like this (scoria doesn't always have a key in it)...

- the beasties live in the grow media. They eat fish crap and crap out plant food.
- interestingly a stack of fish eat plants, and those that don't, tend to eat things that do, so the entire thing can just go around and around for ever. Which is nice.

Those bacteria also eat fish food (or at least they eat the stuff that fish food will break down into), so any food not eaten eventually breaks down and gets absorbed nicely into the system (within reason).

By adjusting the height of the siphon's standpipe its possible (and desirable) to set the flood depth of the grow bed. Set high tide to a point just below ground level. I'm told 2.5cm below ground level is about right. Plants don't like to get too soggy and the bacteria don't like light so there is no point in over filling and its just going to waste more water to evaporation if you over fill the grow beds (I'm told aquaponics uses only about 10% of the water you might use on a dirt garden). Its also a good idea not to fill your grow beds all the way to the top with gravel either. Over filling your beds with gravel will end up with you spilling your media onto the ground every time you dig around or harvest a plant.

My grow bed takes around 20 minutes to fill, and around the same time to drain.  The pump runs all the time so water is flowing in the entire time, even when its also flowing out.

As a rough guide your media takes up around 60% of your grow bed leaving space for water in the other 40%.

Aquaponics - Flood and drain

Plants seem to like it when their roots are not too wet and not too dry. Goldilocks would have us set the moisture level juuuust right, but in aquaponics, there is a better way. Flood and drain.

In our blue barrel system (pictured here at day one) we have half a barrel at ground level as a fish tank, and half raised above the fish tank as a grow bed (within the online forums you will see FT as fish tank and GB as grow or garden bed)
This allows us to pump water up to the grow bed and have it drain back down with gravity. But rather than have it running all the time the plants prefer to get some water, then some air, to their roots. One very simple way of doing this is to use an auto-siphon.

An auto-siphon allows us to fill the grow bed with nutrient rich water to a predetermined level, and then have the water dump back out into the fish tank bellow, exposing our plant's roots to the air. Plants love that kind of thing. And the fish love the circulating water. Keeping the water moving oxygenates it and running it through the grow beds filters it.                               

A bell auto-siphon would look something like this if someone were to make an animation of one working ...

- water is pumped in at the top from the fish tank (FT not shown)
- when the water level rises to the top of the standpipe (the standpipe is the innermost pipe) it starts to overflow.
- As the standpipe fills and the water flows down the tube and back into the fish tank, it forms a siphon.
- the small amount of air left at the top of the bell (the bell is the bit that surrounds the standpipe) is sucked down with the water and the grow bed quickly drains back into the fish tank.
- when the grow bed level gets to the bottom of the bell the siphon is broken and the draining action stops
- the water is always running in but the siphon is designed to allow water to flow out faster than it comes in
- the result of this is a flood and drain cycle that plants love.

Other beasties in the grow bed love this flood and drain as well but more on that later.


Twitter updates to indicate the start of a new topic.

Aquaponics - fish mortality

From what I've read about this aquaponics thing, there is a possibility of losing fish to disease, accident or to the plate. I intend to show any catastrophes/recipes as they occur.

Aquaponics - an ecosystem in a barrel

There are a stack of 200 liter blue barrels on the planet that were once used to transport things like softdrink syrup. We needy people all over the globe never seem to have enough soft drink syrup and throw a lot of these onto dumps, into recycling depots, and more often than you might think, just directly into the ocean.

Aquaponics turns blue barrel flotsam into fish and vegetables.

Is there anything aquaponics cant do? :)

Travis Hughey was way clever when he first used blue barrels to grow food (he probably still is clever)

The plan is to create a small test system with a blue barrel, then apply my new knowledge to a larger system that will be capable of feeding us. I've already started.


It turns out aquaponics is an amazing system of growing food.
It's all about creating a tiny ecosystem in your backyard.
In essence, you get some fish to crap in some water, then offer that water to some plants.
The plants gratefully take all the nutrients out of the water and offer it back to the fish to crap in again.
The water cycles around forever and you add a bit to replace evaporation and whatever the plants use.

Inputs into the system are

-fish food

Outputs are

- vegetables or flowers
- fish (or not -  you can just use goldfish)

I'm going to have a crack at it (actually I've already started).

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