Backyard Aquaponics

[Bidadisndat]

This site is well worth having a look at: Growing fish and vegetables in a mutually supportive system that does not require the input of insecticides, herbicides or fertilizers, uses far less water than a regular garden, and if properly planned can be run by a solar power set-up. www.backyardaquaponics.com

[opsec]

I remember Atash saying that tilapia are a particularly hardy fish. I bet they would do well in these kinds of systems. Isn't there a way to put water plants in the same tank as the fish so the fish just nibble the plants for their food supply?

[Bidadisndat]

Don't see why not. On the other hand you could have a small tank in the system to grow something like duckweed that you could harvest regularly and throw to your fish. (And that duckweed multiplies like wire coathangers in a dark closet.)

[Lady Lilya]

How come my coathangers never multiply?  Do you think my closet isn't dark enough?  I never seem to have enough hangers.

[Bidadisndat]

I think the local IVF centre for those things is called a dry-cleaners.

[Lady Lilya]

I haven't been to a dry cleaners in probably about a decade.

[Atash Hagmahani]

I remember Atash saying that tilapia are a particularly hardy fish. I bet they would do well in these kinds of systems. Isn't there a way to put water plants in the same tank as the fish so the fish just nibble the plants for their food supply?

Well, Tilapias are EASY to raise, but when we say "hardy" we need to exclude "to cold". It's a tropical fish (mostly), not adapted to cold water.

Yes, they will eat plants growing in the water, like duckweed and probably stuff like "water lettuce" (not really lettuce--weedy tropical floating plant that spreads like crazy). But it would still make sense to throw garden vegetable debris (plant parts humans don't eat) from the garden into the Tilapia tank. You can raise Tilapias pretty dense because they are partially air-breathers anyway--that's how they deal with stagnant water in their native African lakes.

[opsec]

Could such a self sustaining run indefinitely? It looks like it could as long as you have something to feed the fish with.

[Atash Hagmahani]

No, that would violate one of the laws of thermodynamics, but if the fish feed the plants and the plants feed the fish, that is a pretty darn efficient system. That's why I plug it.

[opsec]

Oh, I know that it wouldn't run like a perpetual motion machine. I was just wondering if it would be self sustaining for a period of years or if it would die out quickly.

[Bidadisndat]

You'd have to do some regular maintenance on the system, Opsec, though it's pretty much a minimum.
There is also a need to add some trace elements to keep the vegetables in the grow beds really healthy. One way to do this would be by the occasional addition of some 'worm oil', (the liquid run-off from a worm farm), to the beds. That would not cause any problems for the fish either.
I've got an old 12' diam. above-ground swimming pool that I'm trying to set up for growing the fish, (silver perch), with, so far, 6 old bath-tubs for the grow beds, (need 4 more), plus 10 small worm farm kits. My idea is to set everything up as a continuous cycle system: Fish detrirtus/urine/excreta supplies ammonia to the grow beds, wherein nitrifying bacteria converts it to nitrites, then nitrates, which are taken up by the plants. The water returning to the tank is clean and oxygenated during the process. Some of the water from the fish tank to be used to water the worm beds attached to each grow bed, and some of the worm oil allowed to flow into them occasionally. Some of the worms can be used to help feed the fish, and some to feed to our chickens. Excess worm oil and the worm castings will be used on the organic vegetable beds, of which we currently have 10 (5' X 12'). Originally had 20, but we got flooded out 4 times, and it's taking time to rebuild them all.

[opsec]

Souds cool. Pics please. Why do you use gravel in the growing beds instead of topsoil or even regular dirt?

[Bidadisndat]

Sorry Opsec, but pics will have to wait until we've got a new camera to replace our broken one. As for using gravel in the grow-beds, topsoil/dirt would simply be washed away by the ammount of water passing through the system. 'Aquaponics' is basically a combination of a hydroponic vegetable growing system, and a tank of fish being grown out for food (aquaculture), to provide the nutrients, instead of using a soup of chemical additives.

[Atash Hagmahani]

instead of using a soup of chemical additives

Which by the way will not be available once the system breaks down enough (at least, not in any part of the world I am liable to end up in). Hence my interest in a lower-energy alternative.

[Bidadisndat]

Absolutely, Atash. Backyard systems can also be run using solar powered pumps, which is another plus.
BTW, if the water pumped from the fish tank is run through a fine mesh filter before going into the grow-beds, the solids collected there can be put into the worm-farm. (See seperate thread.)