Aquaponics - Sequencing

An ideal aquaponics system has twice as much grow bed as fish tank. The problem is, once you have twice as much grow bed as fish tank, when the tide is out your fish tend be walking around slightly more than fish tend to enjoy. The grow beds takes so much of the water that the fish tank becomes uncomfortably low.

If you fill one grow bed, and then the other in turn you will remove less water from the fish tank at any one time as there will always be another garden bed draining water back into it. There are a few products you can buy to achieve this, but pictured here is my first attempt at in invention to make this occur. Basically its a sea-saw where water is diverted from one side to the other when a float raises to the point where the sea-saw tips, diverting water to the other side. The sea-saw's floats are set at just the right height so that it tips to the other side just before the auto-siphons trigger. The siphons are triggered by the other smaller flow (water flows are all constantly on, and are pictured here as the blue arrows pointing down from the top) I made one of these and it seemed reliable enough even though it looked a bit like it was made by Homer Simpson. 

I don't intend to use a sequencer in my system as I'm going to use CHIFT PIST (Constant height in fish tank, pump in sump tank) which means there will be plenty of water for everything. If space is a problem a sequencer may be the solution. Aquaponics often involves compromise when building a system, especially on a budget, so I thought I would post this just in case it is useful.

[edit from the future - There is some additional material on sequencers. Readers might find this newer version in a post titled  The Bullwinkle sequencer build of interest. It's a better design, and only costs around AU$15 to build with off the shelf PVC components]

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.