Basic Greenhouse Aquaponic System

While I’m keen to see how much food we can get out of an Aquaponic system setup in a cold garden in the North West of England, I think I’m going to try and restrain my “bull in a china shop” enthusiasm and start off with a small development system. Once that’s balanced and working, I’ll be ready to develop a full system with the aim of providing year-round food for our family.

With that in mind, here’s my hastily sketched initial system:

It’s a flood-and-drain system, all housed in a standard 8′ x 6′ greenhouse, with a 500 litre fishtank and two 320 litre growbeds. I’ll post details of it on the Backyard Aquaponics Forum and see what the experts think before I do too much more development.

Basic Design Guidelines

In designing an aquaponics system for your garden there are a few basic guidelines that seem to work. They cover things like the amount of fish you can stock, and the relative size of your tank and growbeds. Here are some of the main points:

• Ideal depth of the gravel in a gravel-filled growbed is 300mm – this allows for the best conditions for plant and bacteria growth.
• Use a 5-10mm particle size gravel for the best surface area for bacterial growth – smoother gravel makes for easier planting.
• Maximum advisable stocking level is 6kg of fish per 100 litres.
• Growbed volume should be twice the volume of the fish tank.

That should be enough to get me started on my basic design!

What is Aquaponics?

Aquaponics is the combination of Aquaculture (keeping fish in tanks) and Hydroponics (growing plants without soil). It aims to solve the problems of both of these methods, delivering a system requiring very little water or added fertilisers.

A working aquaponics system needs three things: fish, plants, and beneficial bacteria. Working together, in balance, these power a successful aquaponic system. In a typical setup, ammonia-rich water from the fish tank passes into gravel growbeds colonised by the bacteria; the bacteria convert the ammonia first to nitrites and then to nitrates, which are then the perfect fertiliser for plants to grow in the growbeds; the cleaned water then returns to happy fish in the fish tank.

Why bother? There are lots of reasons:

• Plants in an established aquaponics system tend to grow up to 3 times faster than in a traditional garden.
• Very little ongoing water is required – great in a drought.
• The plants require no extra fertilisers.
• You get delicious fish to accompany your fresh garden vegetables!
• You can have an aquaponics system in your own back garden.

In a world where our food is becoming increasingly expensive, and with the effects of Peak Oil due to make food availability even more critical, an Aquaponic system in your back garden could make a real difference to your diet and expenses!