Not sure whether it’s the joy of finally finding a house for us to settle in for the next decade-or-so, or whether it’s the delight at finding a garden that, due to its orientation and terracing, is perfect for a garden split between agricultural and familial duties. Or is it just that spring is in the air? a glorious spring at that!

Whatever it is, my mind is embracing the possiblities of our new situation. A situation that lends itself to a no-holds barred aquaponics system. Gone is my initial timidity. Stuff it, let’s go straight to a BIG system. One that’ll feed the family, and then some.

To maximise its potential, we’re going for a system that is referred to as CHIFT PIST (Constant Height In Fish Tank, Pump in Sump Tank) or CHOP (Constant Height – One Pump). Essentially what this means is that the fish can remain serene, and undisturbed in their tank, with a large sump tank handling all of the variation in water height as water is pumped through to the growbeds. Here’s how it works:

  • The system starts with the sump and fish tank full of water, and the growbeds empty.
  • A timer turns the pump on – the pump is located in or near the sump.
  • The pump transfers water from the sump to the fishtank.
  • The fishtank overflows, passing water to the growbeds by gravity.
  • The growbeds fill with water, while some starts to flow slowly out of the growbeds to the sump.
  • With the growbeds full, the timer stops the pump, and the fishtank stops overflowing.
  • The water from the growbeds drains under gravity into the sump.

So it only needs one pump, a timer, some careful pipework and a sump large enough to handle all of the water from the growbeds.

Following my last post on Greenhouses and Polytunnels we’re going for a HUGE polytunnel. Would love a greenhouse, but for the size that we’re after it’s not in our budget. Here’s our proposed system:

Large Polytunnel Aquaponic System

Large Polytunnel Aquaponic System

It’s a bit of a monster! Here are the details:

  • The fish tank (rear right) is 6’x4′ and 4′ deep – 2700 litres
  • There are three rows of growbeds : Ten that are 4’x2’x12″, and three that are 7’x4’x18″ (although these will only be filled to a depth of 12″).
  • Total growbed volume – 4300 litres.
  • Growbed:Fishtank ratio is 1.5:1
  • The sump is made up of three interlinked tanks,7’x4’x18″.
  • Total sump volume is 3050 litres.
  • Sump:Growbed ratio is 0.7:1

So those are the tech specs, what does it mean for food? This system should provide more than enough fish and non-root veges for a family of four – that’s my estimate, based on other systems I’ve seen. That’s our target – at least from year 2!

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