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Thursday, December 13, 2012

Apartment Aquaponics 101.

Aquaponics: essentially a (beautiful) marriage of aquaculture and hydroponics.
Aquaculture is fish farming.  Fish are grown in ponds or tanks (or giant net enclosures in a lake or bay), like a feedlot for fish.  With aquaculture it’s possible to produce a lot of high quality protein in a hurry.  But all those fish so close together create a lot of nutrient-rich waste!  In open water this is not quite so much of a problem (it’s still a problem) but in ponds or tanks it is a HUGE problem!  The water needs almost constant pumping/filtration just to stay liveable!
In hydroponics plants are grown without soil, all the nutrients they need are brought to them in water.  The plants are either suspended with their roots in the water or supported in a moist “soil-less medium” either pea-gravel, “expanded clay” or, in my case, aquarium gravel.  The benefit is plants can be grown closer together because they don’t have to compete for nutrients, the drawback is all those nutrients need to be supplied by the farmer, usually in the form of nutrient-rich liquid fertilizers.

So, plants grown hydroponically need nutrients in liquid form,
farmed fish produce a lot of nutrient-rich waste-water.

Enter aquaponics!  The fish poo and pee in the water which is pumped up to the level of the grow-bed (where the plants live).  The water trickles down through the “soil-less medium” and is filtered by the hungry plants (which feed on the waste produced by the fish) before falling back into the fish tank.  Simple.
Well, not really.  There’s more to it than that.  We’re going back to science class.
Fish produce ammonia (NH3), which in its raw state is poisonous to plants.  We need bacteria, called nitrosomas, to convert the ammonia into nitrites(NO2).  Unfortunately nitrites, while not poisonous are, as far as we’re concerned useless.  We need to convert them to nitrates(NO3) which the plants can “eat”.  There is a bacterium to do this too, its called nitrobacter.  Fortunately both will develop naturally if given enough time.
So now; the fish create ammonia in the water, bacteria in the tank convert the ammonia into nitrates, the water (with nitrates) is pumped up to the grow bed where it is filtered by the plants before returning to the fish tank!

And that, boys and girls, is how it all works.
To any teachers reading, this would make one hell-of-a science project. 

I wanted to try aquaponics for myself.  It sounded so simple and so interesting!  And think about it, scaled up an aquaponics system could be used to grow alot of food!  Especially after last summer I was definitely thinking in terms of food production.    So I started doing some research.  By far the best web page I found was Hydroponics plus Fish Farm equals Aquaponics; a how to, it describes EXACTLY how to make an aquaponics system in a greenhouse.
But my girlfriend and I live in an apartment! There just isn't enough room for a greenhouse and all that equipment!  So I did what I always do in these situations.
Pay a visit to Value Village.

And this is what I came up with!  It’s a little (2 1/2-3 G?) fish tank.  I picked it up, along with pump and grow-bed (that black box with gravel in it is the grow-bed (used to be for a filter?), the piece hanging down on the left is the pump) and a fluorescent light (which I don’t expect to need) for about $11 (after tax).  Gravel was about $7 for a 2kg bag.  The pump was working to fast and totally flooding my grow-bed (that not good) so I stuffed a piece of sponge in the outlet (that’s that little yellow thing).
Tomorrow (after the water has had a chance to sit a little and the temperature has stabilised) I’m going to add a few feeder goldfish.

Expenses so far: $18.

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