What do you get when you cross a tank full of fish and a vegetable garden?
You get a very productive food producing system called Aquaponics!
Over the weekend I ducked down to my local nursery and ordered a Balcony Kit aquaponics setup. I wish I had the balcony to put it on, but the kit is small enough to fit comfortably in a small space. Measuring only 2.7m by 1.5m and 97cm high there are three grow beds that have the capacity to feed three people consistently (both fish and veggies).
Aquaponics works on the theory of growing plants in an inert media such as expanded clay pebbles with an ebb and flow water system, as is done in an hydroponic setup. The similarities of the two systems end there. Where hydroponics requires the regular addition of nutrients to the water, aquaponics uses fish to create nutrients.
The system works by adding fish food to the water, the fish eat the food, their by products are pumped into grow beds where natural bacteria turn ammonia into nitrogen which plant roots suck up and grow prolifically. Nutrient free water is then drained back into the tank for the process to start again.
Not only do you get a supply of vegetables, but as the fish grow to plate size you can take them to the kitchen as well!
So why am I giving away growing most of my vegetables in dirt you ask? Living in a tropical environment there are many problems I have found when growing in dirt, I’ve had more than my fair share of fungus, mealy bugs, weeds, birds, ants, weeds etc to deter the most enthusiastic gardener from even trying to get their plot growing to any kind of respectable standard. Not to forget over watering, under watering, over fertilising, under fertilising, digging the soil, conditioning the soil… the list goes on!
Call me lazy, but given my hectic work schedule these days the time to spend in the vegetable garden is getting limited (especially in the cooler months with less daylight hours!). I’ve see aquaponics as a way of getting the best food home grown food for my family as I can with less time input, or working smarter instead of harder!
So you can only grow leafy greens in aquaponics?
Not at all, many forums such as AquaponicsHQ and BackyardAquaponics have members that have had great success with root vegetables such as Beetroot & Carrot. Other popular vegetables include Corn, Peas, Beans, Tomatoes, Cabbage, Chili, Capsicum, Lettuce, Broccoli, Cauliflower, Egg Plant, Celery, Strawberries… Murray from Aquaponics.net.au has even grown a PawPaw tree!
As the system is almost closed, the fish food is the only main additive, there can be times where plants become stressed due to nutrient deficiencies. Iron, Magnesium and boron deficiencies can be common, especially when your plants are getting large. Cheelated Iron, Epsom salts and borax can all be added safely (in small quantities) to the water without detriment to the fish. To reduce the need for additional nutrients a high quality fish food with a full range of minerals should be used.
Unlike dirt gardening, where you can get away with a squirt of insecticide now and then, any form of pest control in an aquaponics system must be organic. Should you go through with a dose of insecticide there will be a tank of floating fish. White oil, chili and garlic sprays and diluted milk will be you new best friends.
The planting density in an Aquaponics setup can be fairly thick given the even spread of nutrients from the water. Reports from forums state that you can plant most things at around half to 1/3 of the spacings that are recommended for dirt gardening. This won’t apply to plants such as cabbage or possibly tomatoes which spread to a large size.
Right now, I’ve got the area measured up, some seedlings getting ready to transplant, and another week or so to wait till my kit turns up!