Backyard Aquaponics In Gerringong

On Sunday, I visited John Burgess at his home in Gerringong. John is the owner of Fresh By Nature, the official NSW distributor for Backyard Aquaponics systems. He is also active in the Backyard Aquaponics Forum, the biggest and most active aquaponics forum in the world with almost 2,500 registered members, running aquaponics systems all over the world.

John showed me around his various hydroponic and backyard aquaponics systems, and it was utterly fascinating!

First, a definition: Aquaponics is the symbiotic combination of aquaculture (fish farming) and hydroponics (growing plants in nutrient solution rather than soil) in a closed system. “Backyard aquaponics” simply refers to doing this on a household scale, rather than a commercial scale.

Basically, water is pumped around the aquaponic system from the fish tank to the hydroponic grow-beds and back again. Ammonia produced by the fish (through respiration, food waste, excrement, etc) is carried by the water to the grow-beds, where it becomes (via bacterial conversion) nutrient for the plants. The plants absorb the nutrients and filter the water, so that clean water is returned to the fish tank.

When all the elements of the system are in proper balance, the only inputs into the system are fish food and water top-up to replace evaporation/transpiration losses.

John has many years of experience in both commercial hydroponics and home based hydroponic food production, and is certified in aquaculture as well. This gives him a great background for combining the two in aquaponics. As we walked around the backyard John pointed out various experiments in progress. I was particularly interested in the solar powered aquaponic system that is nearing commercial readiness and should be available soon.

I was surprised to see rosemary growing happily aquaponically. Everyone always says it’s a great drought-tolerant plant, and that it hates to get its feet wet. John explained that it’s not so much the water that plants like rosemary can’t handle, as the lack of oxygen. Because the aquaponic water is highly oxygenated, as well as being delivered in a flood-and-drain pattern, the roots are not drowned at all.

Even more surprising to me was that the grow-beds all have worms living in them! Again, it’s because they can tolerate the oxygenated water flooding and draining from the grow-beds. The worms live on organic matter that falls down into the growing medium, as well as roots left behind by harvested plants. Their worm castings must be great fertiliser for the plants, too.

An interesting aspect of backyard aquaponics is that you have to be “more organic” than most organic growers would ever dream. Any chemicals you spray the plants with will likely kill your fish. Similarly, you don’t want to treat fish problems with chemicals if you’re going to be eating either the plants or the fish. So you end up using very basic plant treatments like garlic or chilli sprays (definitely no soaps!), and simple fish treatments like salt dosing.

As well as the fish, John had yabbies and freshwater mussels growing in his aquaponic tanks. The mussels are very efficient at cleaning the water, and the yabbies give an additional yield from the system without affecting the fish stocking levels much.

A typical starter backyard aquaponics setup consists of a 1000L fish tank and two 500L grow-beds. Such a system will set you back a bit over $3000 as a ready-to-go kit. A backyard aquaponics system of that size would provide fresh vegetables for a two-person household, and around 30 fish of about 1kg each over a 12-month period.

Of course you can also build a DIY aquaponics system, and there are plenty of examples of these on the net. While John sells complete systems, he is also happy to supply just the bits and pieces you need if you choose to build your own. He’s genuinely more interested in seeing more backyard aquaponics systems set up than in merely flogging his own products.

You can grow all kinds of freshwater fish in these systems – John sells Australian bass, eel-tailed catfish, Murray cod, silver perch, trout, and WA black bream fingerlings. He also sells yabbies and freshwater mussels.

I’ll follow up with more information on backyard aquaponics in a few days’ time, but meanwhile here are some photos of John’s systems (some photos are mine, some are John’s). Click to see larger images, then click on the left or right half of the photo to go backwards and forwards through them.