The yard has been broken up into 7 zones with different purposes and I am trying to work my way through one zone at a time as working on the whole lot was beginning to overwhelm me. I want each zone to act like a room and have some degree of screening or separation from the others.
There are 12 bathtubs going into this zone which are plumbed up to allow the water to recirculate from a 7000 liter fish tank around and back to a collection sump made from 2 large cast iron tubs.
The growing tubs are supported on rock block pillars that are filled with cement and reinforced internally with scrap steel bars. Under each pillar I cast a large cement block to create a stable platform.
I was really worried that the tubs wouldn't be able to hold the weight of the gravel when supported just on the their ends so I tested one of them for a couple of weeks and it held up well. The tubs have been in for 8 months now and there has not been any obvious signs of stress.
Supporting the tubs from the sides would be a preferable means of support but doing it this way allows them to be placed along the fence line with very little space wasted. I wouldn't do this with fiberglass tubs and haven't tried it with cast iron tubs so I don't know how they would go.
I am now adding a timber facade to the tubs to make them look more attractive and give me some extra storage places for pots and PVC pipes. They will eventually be painted the same cream colour as the house and shed.
This wooden framing is blatant plagiarism of the excellent work that Bill M did on his Aquaponics System. Bill was kind enough to give me some pointers when I started. There are access hatches with removable panels to allow maintenance of the internal plumbing.
The paneling is just made of garden edging timber from Mitre 10 and works out at about $1 a meter. It works well for this purpose but shouldn't be bought until you are ready to use it as it has a tendency to warp very quickly if it isn't stacked properly and kept dry.
Once it has been screwed into place there isn't a problem and any shrinkage is uniform and looks quite good.
There is one pump in the sump tank that turns on for 15 minutes every hour. It is a large 100 watt pond pump so it is only drawing 25 watts an hour which puts little strain on the houses solar panels.
The tank currently has 100 Jade and Silver perch in it including a few very large ones (about 5 years old) that were given to me by Graham F. These fish were originally part of Central Queensland Universities Aquaculture program and were given to Graham when they finished with them. Graham has had them for the last couple of years and gave them to me when he moved. I wont be eating these big fish and will keep them as pets. I also have a theory that the reason people have difficulty breeding perch in tanks is that their stock are so young.
I have been told that perch do breed in dams and have read somewhere that they may react to a change in temperature, rise in water level and the scent that comes from dried grass washing into the water ways that trigger their breeding activity. I have no idea if any of that is true so if you have some hard facts please make at a comment to this post and let us all know!
There are also 50 fingerlings that Geoff and Llyn S gave me yesterday when they moved into town. They don't live to far from me so it was a good way for Llyn to put the fish somewhere where she can watch them grow up.
I originally covered the surface of the tank in duckweed when there wasn't any fish in there but have covered it up with tarps to stop the algae from growing. Eventually I will find a more attractive cover for the tank.
When the weather starts to warm up I will be adding redclaw to the tank. They shouldn't have any problems cohabitation with the perch and I will make sure that they have lots of structure for them to hide in. Jade and Silver perch generally won't bother crayfish and are more interested in the vegetation and pellets that are added to the tanks.
I am trying to make the yard as easily maintainable as possible and have been putting in cement edging that I can wippersnip up to. I am also building some boxes that will go around the fruit trees in the orchard/permaculture zone and have been getting my sisters children to paint them.