Closed ecosystems

I was tidying out the greenhouse not long ago and in one of the tubs I found a nice crop of potatoes. It was a bit of a surprise as I had not been in there for a while and nothing in there had been watered except for my grape. It appears that enough water was splashed to keep it going and the plants had kept themselves going in a cycle for some time with the potatoes growing, dying and growing again. The worms were doing a great job of keeping the soil in tip top condition. Until I had arrived and interrupted the cycle it was doing well. My first experience of a closed ecosystem for food. I’ve had experience of closed ecosystems before. These were for decoration though, a brine shrimp container with the poor buggers sealed in until it just overloaded and died and a very expensive ecodome that although sealed took sunlight as power and the source of the algae to keep going. The brine shrimp version was always on a short timer whilst the other one was expected to last years.

These were my only real experiences with closed ecosystems for food production but I’ve looked around since then at other systems and how they are set up.

At the moment I have several plants in pots all around the back garden. I’m looking at expanding that next year with a fish farming facility to breed fish in. As with all my prepping I’m looking at a smaller system to use as a starter for if an event occurs. Moving to a larger set up after an event. It helps with OPSEC and minimises space requirements at the moment when space is an issue.

Even so, a small ecosystem still requires a lot of space. So what can I fit in my garden?

Simply put aquaponics is hydroponics with the addition of a fish tank which takes it one step closer to a closed ecosystem. This means I can starts with a fish tank filled with fish and water, the fish eat plants, grow and produce waste. The waste from the fish contains nutrients that get passed to another tank full of food plants which uses the nutrients, fertiliser, to feed the plants. If you include the initial plants for feeding the fish then this is as closed an ecosystem as you can get. The only real external inputs are sunlight and, ideally you put scraps and insects in for your fish to feed on.

I’m looking at setting up a fish section about the size of a kids paddling pool but higher with a larger volume of water, a water cascade into the pool to increase oxygenation and a flow pipe from the bottom to the plant areas. The water will then flow through the systems until it reaches a holding tank where it is pumped up into the cascade above the fish tank.

The fish tank can just have scraps thrown in but it can also have insect facility. This insect facility is basically a cupboard of flies. Simply make a cupboard with a few shelves and a door to add food waste like meat in such a way that the flies cannot escape. The bottom is removed and the sides extended by mesh down below the water line. Drop the meat in the doors, the flies eat and lay eggs which grow into maggots. Some of the maggots fall into the water and feed the fish while the remaining maggots live growing into flies, some falling into the water as well. Add a small bit of meat to a new shelf and let the old meat and maggots fall into the water and the cycle continues.

Starting the colony is easy enough. Build the cupboard and install. Leave some meat outside on the window ledge until you see maggots on it. Put it into the cupboard and wait.

Anyway, that is on my plans for next year and I will be looking at the best fish to put in. Something that can be eaten, taste nice and something that will thrive and grow in such an environment. The plants are easier as they are just what you want to eat and a little something for the fish.

On a final point, the only part that won’t run on its own is the pump for the water return. In an event we could put a solar pump in as there are several available for small ponds but I’m looking at making it completely self contained if I can. Where are my plans for a perpetual motion machine?