Saturday, October 1, 2011

Aquaponics and Salty Garden Tales

Hi Folks, aquaponics and fishy tales.                                                                                                       

Neville and Anita  heard our story about how Ivan and Margaret were catching dinner plate size perch from out of the old swimming pool in their back yard. “Come and have a look at this” he said.
Turns out that after arriving in Gero from Cervantes they set about, with the help of Father in-law Dwayne,  to build a Aquaponics set up under a shade house in their back yard.  A year later with info from the enthusiastic bloggers on the net and local knowledge he ended up with what looks like a small sailing ship with leafy vegetables climbing up the masthead and silver perch swimming around the bottom of the captain’s cabin!

This was a 2500 litre fish tank cut down and holds over one hundred silver perch. The front garden part is at optimum depth of 300 mm of pebble gravel. There is no weeding, no fertilizing and no bending over. The fish are fed a commercial feed and an occasional lettuce leaf or beetroot leaf. (We have seen people feeding tadpoles with spinach leaves!) 

The fish poo sends out ammonia which is turned from a nitrite into a nitrate. This residue is really good for leafy vegetables like climbing spinach, lettuce, tomatoes, beans, cucumbers. But not much good for root vegetables like potatoes, turnips etc, however he has tried beetroot with good results so far. There was trouble with cabbages not balling up. Turned out the rats got on the ship and were eating the cabbages (sounds like a sea story?) So they got rid of the rats and switched to leafy cabbages like Bok Choy and can peel the leaves off as they want, strawberries go really well as do mushrooms.                                       

Two parts per million of salt was added to the water at one time to help the fish stay healthy but the balance of that in relation to the plants needs watching. The water only ever gets to 30mm under the gravel for the plants and every fifteen minutes it goes back into the sump tank through bell siphons placed around. Worms were added and are thriving in the gravel! Every two weeks Neville checks the ph and alters it with eco rose or lime but recently put some shell grit into the tank and the water extracts the calcium and balances the ph to optimum of 6.4 to 6.6, so that is working. Once a week the tank is topped up with a hose for about a half an hour and that is all the water that is ever added. It doesn’t evaporate much from 30 mm below the gravel and the only other water used is by the fish and the plants.
                                                                                                                                                             
Snow peas growing up the rigging had to be harvested with a ladder across the yard arm! And huge cucumbers looked like cannons pointing out to sea.

The tank with the fish in it is large enough to support three or four more beds but the cost of making them in material and time left them on the back burner. It took about a year for the water to reach the optimum level of good bacteria with the right level of ammonia, nitrites and nitrate. There is a site on the web called ‘backyard aquaponics’ down in Perth and another called ‘practical aquaponics’ both with big forums with plenty of information. Their efforts were a lot of trial and error at first but the forums did help. “You gottta have a backup battery power supply for air to the fish or they will be dead in half an hour” . There is a dirty water bilge pump which circulates the water back into the fish tank and keeps the poo moving, the fish like it!
Next to the ship shape fish and garden are small tanks called wicking beds with the bottom 200 mm filled with vermiculite, then a layer of shade cloth then 300 mm of good potting mix. A pipe directs water to the bottom and the water then wicks up to the plants, no waste of water. Potatoes and Zucchinis grow in them. They are building rain water tanks to harvest water for these beds off the house and shed.
                                                                                                                                                           
The rest of the back yard held a chook pen, grape vines, passion fruit and citrus trees with the odd cactus. Anita has her red rose’s which are her show piece out the front of the house in this unusual and well kept
garden
                                                                                                              

Telling Bob about all this over a beer later, he said to me. “What happened to the days when we were kids in the old clinker dinghies that we rowed out and had fun catching fish. Now you walk down to the flaming back yard and there they are! Got me beat what will happen next.”
“Takes a lot of time and effort to make all this happen” I replied “and it seems a lot of gardeners are conscious of looking after our planet these days as well as feeding themselves fresh food from where they live.”

A readers.Question;
Sue asked "How do I get rid of fruit fly in the orchard?"

Answer;
Mediterranean fly is the common pest of fruit in W.A.
The first and most important step when attempting to prevent fruit fly attack is good hygiene. Keep the ground under the trees clean. Mature maggots pupate in the soil to remerge as adult flies and collecting infested fruit breaks their lifecycle
To kill the fruit fly maggots, immerse them in a sealed bucket of water for a couple of days or put them in a sealed plastic bag and put it in the sun. If you have chooks, they will appreciate them!
Trapping adult flies helps limit the breeding population. Josh Byrnes says, "Start by making some holes half-way up a plastic drink bottle. They should be about 10 millimetres wide and evenly spaced." Josh recommends fruit juice for the lure but he also adds a pinch of sugar and a sprinkle of brewers' yeast to make fermenting sweet syrup that, Josh says, "Fruit flies just can't resist." Commercial traps are available as well as certified organic baits.

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