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Backyard Aquaponics

Aquaponics is THE key ingredient in our plan to live sustainably in Namibia! It allows us to produce a lot of food with very little water!

Aquaponics is a system where fish, bacteria and plants work together in a loop to produce lots of food with little water. The fish live in a fish tank. They poo and the dirty water is pumped into the grow beds in which the bacteria live. The bacteria eat the dirt in the water and thereby convert it to food for the plants. Thereby the bacteria clean the water which is then returned to the fish tank.

Image from explains Aquaponics as follows:

“Aquaponics is a system for farming fish and plants together in a mutually beneficial cycle. Fish produce wastes that turn into nitrates and ammonia. These aren’t good for the fish if they build up too much, but they’re great fertiliser for plants. As the plants suck up these nutrients, they purify the water, which is good for the fish.

Many cultures have made use of this cycle to grow better crops and nurture the fish as an additional food source. Rice paddies in China and Thailand have used aquaponic techniques for years. The Aztecs developed a system of building floating islands for food-plants such as maize and squash. Fish propagated around the islands, leaving their waste on the lake bottom, where it could be collected to fertilise the plants.

Modern aquaponics is slightly more high-tech, but it’s still an efficient and environmentally friendly way to produce food. Fish are kept in large tanks and the plants are grown hydroponically; that is, without soil. They are planted in beds with a little gravel or clay balls and their roots hang down into the water. The water is cycled through the system, so that it collects the “waste” from the fish; then it’s pumped to the plant beds, where it is filtered naturally by the plants and can then be returned to the fish tanks.

Unlike traditional farming methods, no chemical fertilisers are needed for the plants: they all come from the fish-waste. It also tends to be organic, because the use of pesticides would be damaging to the fish.

Once the system is set up, only a little extra water is needed to make up for evaporation, because the same water is used again and again. This is a great improvement on traditional plant-growing, which consumes a lot of water. Many types of plants can be grown in aquaponic farms (whether commercial- or home-sized), especially leafy plants and herbs. The most commonly used fish is tilapia, although many others are also suitable.”

The only inputs to aquaponics is water and fish food, which can also be home grown by the ecovillagers themselves, for example by growing duckweed and mealworms!

Aquaponics thus is magic! All pumps can be run on solar, and systems can be built using just pond liner and a shovel! Putting the aquaponics system in a greenhouse will lead to even better results. Importantly – Aquaponics uses MUCH less water to produce food compared to livestock farming!

Here is a great introductory Youtube Series by Murray Hallam. Murray is a guru in Aquaponics and the videos are a great introduction…but they are more a teaser to attend his courses than in depth instructions. They do get one excited about the subject though and they show what is possible.

Saving water

Ideally we’d want to plant all crops in an aquaponics system so as to cycle the water, but a lot more research will be needed to see whether that is practical for all fruit, especially those growing on big trees.

A quick note on water usage. Aquaponics is a HUGE water saver. Evidence from the states suggests that: “Aquaponics lettuce is at 9 Liter per head and at 90 Liter per head of field grown lettuce, Pretty big difference.” – Indeed – this means aquaponics production uses about 10 times less water than growing crops in the field and these results are from wetter climates. In our deserts the difference should be even more startling.

How many fish should you have

One fish (growing to 500g) per 25l of Grow bed. For fish, choose Tilapia Rendalli (Red Breasted) Tilapia, it eats more duckweed and needs less commercial food.

Building the system

Here’s a very detailed video on a system build with three tank system.

Here’s a very nice video of a great aquaponics setup, different kinds of very large beds.

What’s aquaponics all about? Find out as Rob Nash takes us on a tour of his Austin Aquaponics greenhouse where aquaculture and hydroponics unite for water conserving crops. On his rocky land that could never support food, he supplies local harvests all year to restaurants, drop-by customers, and the Lone Star Farmers’ Market from aquaponics media-based and raft beds, along with wicking beds.

Water temperature

Water temperature is important for bacteria, and for aquaponics in general. The ideal temperature range for bacteria growth and productivity is 17–34 °C. The growth rate will get less at 18° C and much less at 10° C. No activity will occur at 4° C.

You can heat your aquaponics water using a solar pump and black plastic pipes. When the sun shines the solar pump will start pumping and the sun will heat the water in the pipe which is then returned warm to the fishtank. At night when it is cold the pump will not run because the sun does not shine so your water will not cool down again.

Seed starting for Aquaponics floating raft

Here are 3 ways to start plants in an Aquaponic System

Here’s a very detailed explanation of Aquaponics showing a high density high yield system in full detail – lots of questions answered.

The best Aquaponics system I have seen so far, even including mushrooms, chickens, black fly larvae etc in closed loops! Produces enough of everything to feed 2 people for a year with 15min work input per day. The design is crowd sourced, modular and opensource…so we can use these designs to build our own. This is the future!

Here’s an awesome Youtube video channel chock n block full of Aquaponics tutorials and tips. Rob Bob’s Aquaponics & Backyard farm:

Building the system

You can build your system from any tipes of tanks. The internet is full of ideas. Most importantly, you need to choose between two different methods of creating ebb and flow in your grow beds. Your plant roots should not always be in water, and they should also not be dry so they need water every hour or so. This can be done in one of two ways: 1. A pump which switches on every hour for 15 minutes, or a pump that runs all the time and you have a Bell Syphon in your beds which let the water out once the bed is full.

Here’s an awesome video on building a bell syphon

Heating your aquaponics

How to heat your aquaponics cheaply

Aquaponics with Ducks

One can also work with Ducks instead of fish.

We can build the ponds with pond liner 30cm under clay – this way we don’t really have contact with the plastic but still we have a watertight pond.

Papaya growing in Buckets in Walvisbay. (

Soil food vs Aquaponics food?

What’s the Difference Between Soil and Aquaponics Farming?

More links:

Aquaponics – DIY Aquaponic Systems – MyAquaponics

FAQS | The Aquaponic Source

Aquaponics How To – The Aquaponic Source Rules of Thumb

Namibia Future Farming Trust Aquaponics

How to Clear Fish Tank Water | Practical Aquaponics Discussion Forum. A place to discuss every aspect of Aquaponics.

Solids Lifting Overflows for Aquaponics

(58) The SanMateo Ecovillage Aquaponics project – YouTube

How to Make Hydroponics Clay Pebbles at Home [LECA, Hydroton]

Aquaponics Stocking ratio calculator

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