Are you making optimal use of your polytunnel? You may be growing plenty of fruit and vegetables for your table – but what if you could create a sustainable system that also provided you and your household with protein in the form of fish? Aquaponics offers just that intriguing possibility – could you grow fish in your polytunnel as well as plants?
Aquaponics combines aquaculture – keeping fish – with hydroponics – growing plants in water rather than in soil. There are a range of different aquaponics systems but basically, the system is designed so that fish living in tanks will add nutrients to water, which is then pumped into a hydroponic system, feeding plants, before cycling back through into the fish holding tank. With sunlight, warmth and water, this system can be an efficient way to grow both plant food and fish and when you also consider 'growing' fish food (such as in a composting wormery) elsewhere on your property, and using solar power, can become an extremely sustainable solution. As well as fish and plants, it is important to understand that aquaponics systems also rely on bacteria to help them to function as they should. Aquaponics systems range in complexity, from simple, home systems to advanced and high-tech commercial enterprises.
So, could you create an aquaponic system in a domestic polytunnel? The answer is a qualified yes. The key to successfully doing so is understanding the requirements of the fish you are using for your aquaponics system and the energy requirements of running the system. Of course you will also need to think about space requirements. A polytunnel is a sensible alternative to a greenhouse for those thinking about an aquaponics system. It will provide the space required, and the protection from the elements required to prevent the system from freezing, for less money than a greenhouse. Of course, if you want to use tropical fish such as tilapia then heating will be needed. Other fish however, such as rainbow trout, for example, can survive in an unheated polytunnel in most of the UK. As with anything else in your garden or polytunnel, an aquaponics system should be tailored to where you live. It is important, of course, to do your research, but you may well find that you could have an aquaponic system in your polytunnel.