Backyard Aquaponics
A place to discuss aquaponics

Hi aquaponicers!

We are busily planning out an aquaponic system and thought I would access the huge amount of knowledge on this forum to help us get it right.

We live in a very arid environment, climate wise we can depend on the following;
Little rain
Very hot summers (usually get a couple of days around the 50C mark)
A couple of frosts over winter
Little cloud
Lots of sun year round
Dust storms and a few days of baking hot wind

We have access to dam water and bore water (which is a bit salty)

At this stage we are thinking of putting a system in a corner of our house yard that has an iron fence to the south and west. We would build a shadecloth fence on the northern side and leave the eastern end open with a shadecloth roof.
We think it would be best to at least partially bury the fish tank in the ground to give it a bit of protection from temp variations.
The tank is fibreglass, 1.2 metres tall and 3.5 metres across.
We are thinking of building grow beds to go inside the tank so as the plants get the cool air coming off the water and the fish have shady spots to hide out. We were thinking one pump in the tank and a flood and drain system. We have old tanks we could convert to grow beds that went outside the tank.
Access to gravel is a bit tricky. We are able to get some blue metal that has not been treated. We think it is about 25mm

Should we look at a continuous flow system to minimise heat stress to plants.?
Is the gravel going to be small enough to provide enough water to the plants?
Is the shadecloth roof going to shelter the water enough to prevent algae problems?

Just the beginning of a multitude of questions.......

Thanks in anticipation

If I were you, I would use a small wattage pump on continuously, and use auto syphons in the growbeds so you can flood and drain. Alternatively, use a float switch or timer. Don't worry too much about your plants wilting, so long as there isn't a huge time lapse between floods.
I recommend shading your pond seperately, as the nitrate levels rise, algae will take hold unless you can keep the sun off. Fish prefer it with a variation in light over a 24 hour period, but not too bright

In a true desert wouldn't you want your AP system to be enclosed in a shed or greenhouse to prevent evaporation?

Incidentally, you can do small scale desalination in a desert really easily. Construct a clear glass/plastic pyramid with a suspended tray for water. The water will evaporate leaving salt behind. Water will then condense on the inner surface of the pyramid and bead down the walls to your collection base to form a pool of (almost pure) water. You can also create brandy from wine the same way

lots and lots and lots of shade for the system and is it possible to bury your tank?

G'day Chrissy, You could have your growbeds near the fish tank and floating foam rafts on the surface of the fish tank to provide shade and protection.. I'd recommend Monyas suggestion of a small pump and using an auto syphon on the growbed to get a flood and drain action..

Floating foam rafts with plants growing in them will keep algal growth in the tank down, though with some fish species like silver perch, a little algae growing on surfaces is fine, they scrape it off and eat it...

Some fish can handle a bit of salt--probably better than the plants. Tilapia (if legal in your area) can handle all the way up to sea water.

I was reading about a guy who wanted to set up tilapia aquaculture in some African desert area. Local people are very hungry and need protein. He was going to drill bores to get salty water to raise the tilapia in. He couldn't get funding because our senators couldn't comprehend why you would purposely drill to get water that wasn't potable. Ahhh, government.

Monyas right n the sun/algae thing. get to it before it takes hold too much.

(julie, if you read this, thats why some floating rafts would be good in your system at this stage)

Thanks for all the replies.

We plan to bury the tank to try to minimise the temp fluctuations.

Wondering about being able to control the shade over the system. Perhaps the fish tank might need a double layer of shade over summer. If we could expose the plants to the sun over winter we would be able to get good use of our sunlight, concern about frost though. We will definitly build shade cloth walls around the system to protect from the wind. We see the wind as being the biggest potential threat to the system. When we get a hot westerly in summer it is akin to opening the door on a fan forced oven!
Is anybody growing plants under a layer of shadecloth? Is there enough sunlight?
Chrissy

we've got our system under shadecloth and a layer of greenhouse film. Of course I haven't actually planted anything yet but very soon
We get very hot westerly winds in early summer. The sides are essentially open on the system (birdnetting doesn't stop much except the birds)

With all that sun it would prolly be a good place for a solar still near by to top up your evap/transperation(?) with nice clean water.

Hi Chrissy,

Good luck and don't loose site of the goal - you may have problems but you can overcome anything you want to if you want it bad enough.

My concern is oxygen levels. The water salinity (which reduces dissolved oxygen) combined with high temperatures (higher temperatures = less capacity for dissolved oxygen) probably means that you'll need additional water aeration.

I think you are best to select your fish species first (a tolerant species), understand their ideal living conditions and range of tolerance and work from there.


LIz

C1 do you mean trapping the transpiration from the plants in the grow bed? How could I do that without heating them up more?
Sounds interesting though,

Chrissy

Sure, C1, W A T E R............. mine is brown and has a smoked peat flavour.........

Steve only to top up with and will prolly have less dissolved nutes...so grow less alge

Been trying to get on the puter for hours...

Chrissy-- the idea has been used since the 1500's apparently..
I was thinking of a stand alone unit with the over flow being contained
http://www.solaqua.com/solstilbas.html
hope this helps...
sorry for my absence...C1

C1, i was talking about the W A T E R that gave you a hangover at my place LOL