Our Aquaponic Polytunnel

Our Aquaponic Polytunnel

OK, here’s the latest iteration of our Aquaponic System. I’ve managed to squeeze another two small growbeds in, and have added the pipes to help show how it works . I’ve mainly been working on the planting list to see how well it’s going to do at feeding us all, and from that I’ve realised that some seedling-prep areas will be required, you can see these lattice-style designs at the right-hand end, designed to be a great spot for sowing and storing seedling prior to planting out in the beds.

I’ve even added a small non-aquaponic bed under the south-facing row of growbeds – shown here in green. I’m going to try peanuts in there as they should like the temperature and they are just the right height to fit under the growbeds. It’ll be an interesting experiment!


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!