Week Eleven

This week the first broccoli and bok choy were harvested, and more bean and peas. The cucumbers are almost ready to eat as well. The broccoli plants take a lot of room, so it looks as though it's better (in a small system anyway) to plant vegetables that keep producing, like bean, peas, tomatoes and cucumbers, rather than big, one-off vegetables. The weather is starting to get quite cool at night (10 degrees celsius) so will turn off the pump at night and insulate the fish tanks and sump to try to conserve heat.

Week Ten

So here we are at week ten and very happy with the experiment. The fish are nearly big enough to wean off the commercial pellets and onto worms (from the worm farm) duck weed (from the pond) and Black Soldier Fly larvae (from the compost bin), and should be ready to eat in 8 months or so. Plus there will always be veggies.

Week Eight

We're eating beans, peas, herbs, Chinese vegetables and lettuce now, and planting new seedlings to replace what's been harvested. Amazing how fast it grows and how good it tastes! There are little broccoli and cucumbers coming on and the tomatoes are flowering. And the fish are growing. How much to feed them is a big question - their feeding rates are affected by the temperature of the water and their size - it's easy to overfeed them.

Week Six

Little beans and snow peas had made an appearance by week six and everything was finally looking quite healthy. We have planted tomatoes, cucumbers, dwarf and climbing bean, snow peas, lettuce, Chinese vegetable, herbs, silverbeet, dwarf broccoli and strawberries. A trellis is installed along the back for the cukes and beans to climb on. There are trellises at the sides for the snow peas.

Week Four

By week four, the plants had really started to grow and a roof and new shade cloth had been installed. One advantage of having your garden at eye level, is that it's easy to spot the pests. Even though there's no problem (yet) with snail or slugs, the grasshoppers and moths can still find it, so at fish feeding time it's a good idea to check the plants and feed what you find to the fish. Also, there are NO weeds!

Week Two

After a couple of weeks, plants and fish were still surviving (except for three that died the night they arrived). Since the little fish weren't putting out much nutrient for the plants, we added some Seasol every day (for a couple of weeks). The shade cloth protects the seedlings at the hottest time of the day.

Seedlings planted

A wooden frame was built to carry a clear plastic roof. If the grow beds fill up with rain, it can disrupt the nutrient levels in the water, so it's best to protect the beds as much as possible. Many people build a greenhouse over their beds and fish, to protect them from the weather and extremes of temperature. However, we live in the subtropics and although we do have the occasional bad storm, extremes of hot and cold are very unusual. Fifty or so silver perch fingerlings were then purchased from a nearby hatchery and seedlings were planted on the same day (April 7) and we were away!

The bathtub sump

An old cast-iron bathtub serves as the sump, with a recycled door installed on top to keep out the leaves and frogs. From here the water is pumped back to the fish tanks by a RIO HF 17 pond pump, which provides enough flow to keep the bell siphons working reliably. The pump only draws 45 amps, so during the day it easily operates on electricity provided by a 60watt/5 amp solar panel installed on the shed roof.

Plumbing

This photo shows how the water overflows from the fish tanks to the grow beds at the front of the shed, then flows down to the sump at the back.

Expanded clay pellets and pipes

Next the grow beds were filled with expanded clay pellets and pipes were installed to bring the water from the fish tanks to the grow beds. This pipe was fitted with adjustable taps that can help equalize the flow of water to the beds. The water exiting the grow beds gravity feeds to a sump at the back of the shed.

Automatic siphons

The white cylinders are the automatic siphons, also called bell siphons, that empty the grow beds of water when it reaches a few inches from the top. The water cycles through the grow bed about six times an hour, and as the water level rises and falls, the both nutrients from the water and oxygen from the air are taken up by the roots of the plants. (An interesting exercise to make these yourself!)

Grow beds

In this photo you can see the grow beds lined up on the nearly finished stand, and to the right, around the corner are the two green fish tanks, on a stand as well. The tops of the fish tanks are higher than the grow beds, so that the water from the tanks will gravity feed to the grow beds, fertilizing the plants, which clean the water for the fish. The buckets at the front are being used to wash gravel for the beds. This soon got very tedious, so we opted for expanded clay pellets, which are lighter, cleaner, and much easier to handle.

Blue drums and fish tanks

We started building the system in early March 2009, using as much recycled material as possible.
The blue drums used for the grow beds are recycled plastic drums used for transporting food. These were cut in half, end to end, and supported on a wooden frame. The green tank is a 500 litre tank (not recommended for potable water, but I didn't know that at the time) that we used for the fish - we have two of these lined up in series.