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.


  1. Not quite on the money, but close.

    The idea is that the Fishtank overflows into the sump, by way of a siphon system, carrying fish waste with it. A pump in the sump returns water to the tank. This circulation remains a constant (and is very similar to the system used in marine aquaria, whereby water falls from the display tank to the sump, where it is filtered and returned).

    A second pump, usually on a timer, sits in the sump and fills the Grow Beds intermittently with water. When the timer cuts out, water flows out of the GB's, back to the sump, to be circulated once again between sump and fishtank.

    The reasoning is that one may place the GBs at a lower, more physically manageable, height, whilst retaining the ability for the water to gravity drain from the beds. Also, as you pointed out, the water level in the FT remains constant, thereby keeping the fish stress free. Any evaproration occurs from the sump, again maintaining FT water levels.

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  3. Interesting. I've never heard of anyone using two pumps.

    What's the advantage over using a single pump in the sump, or if you want to use two for redundancy, putting two pumps in the sump?

    Pumping all your water through the fishtank AND the sump seems like making the best use of the energy used to get the water up to the fishtank in the first place. Once it's up there and overflowing from the fishtank, gravity drops it into the lower, comfortable work height grow beds for free, and returns it to the fishtank filtered of solids, and with some nutrient removed.

    By having your fishtank overflow into your sump, you are putting fish waste directly into your sump.

    I've only ever heard of people using a timer, OR a siphon. Except for me that is...With the possible exception of where someone is using my sequencer, where you would use the timer to switch from one grow bed to the other, and where both growbeds might run siphons, I would think a timer would always be used instead of a siphon, or the the other way around. But not both.

    In my description, the power head is in the fishtank, only to aid aeration, and is run from a battery via an inverter because we lived in a place with constant blackouts. The pump planned for that system was a 150 watt, 5m head pump that was going to pull too much from the battery. The powerhead only pulls 7 watts, but would turn over roughly the same water in terms of aeration, as the pump.(with the head of water the pump would have to deal with in that layout)

  4. This system has yet another advantage. If your growbeds are in direct sunlight and you have few plants or only small seedlings, the grow medium can get extremely hot - particularly in a flood and drain setup. The water entering the sump has a chance to cool before returning to the fish tank and cooking your fish!


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