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Disadvantages of aquaponics

Aquaponics electricity cost

If aquaponics is such an elegant, created ecosystem, why am I down on it?  Simple --- electricity use.

Indoor aquaponicsFirst, there's the pump (or pumps) used to push water out of the fish tank and into the grow beds.  Next comes the energy used to heat the water --- to ensure the bacteria and worms stay active enough to convert fish waste into nitrates, most people keep their aquaponics systems running at or above room temperature summer and winter.  And then there are the grow lights since many people run aquaponics systems inside to get more control over the environment.  To be honest, once you pour all that electricity into the system, I'm not so sure aquaponics is any better for the earth than mainstream agriculture.

Next, there's the fish food to consider.  Although aquaponics looks like a closed loop, it really isn't --- nearly everyone just buys large quantities of commercial fish food to nourish their tilapia or goldfish.  Granted, fish are more efficient at converting feed to meat than other forms of livestock, but you're still basically running a fish CAFO (and contributing to overfishing since most fish feed contains wild-caught fish meal.)

Australian aquaponicsAquaponics arose in Australia, and there it makes much more sense.  Throughout most of their continent, Australians experience moderate-enough winter temperatures that they don't need to bring their aquaponics systems indoors.  And rain is scarce enough that minimizing water use may trump minimizing electricity consumption.  Aquaponics also has potential in other subtropical and tropical climates, especially in cities where good soil is scarce.

The other place where aquaponics shines is if you consider it a way of growing high-density fish with the plants just being a side note.  Wild-caught fish and factory-farmed fish both have environmental problems attached, so it makes sense to try to come up with a more sustainable solution.  That assumes, of course, that you actually eat the fish in your aquaponics setup, unlike the author of Aquaponic Gardening who came to regard her tilapia as pets.

Learn to raise chickens on wild food in Permaculture Chicken: Pasture Basics.



This post is part of our Aquaponic Gardening lunchtime series.  Read all of the entries:





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Hi Anna,

I suppose you wouldn't call what Sepp is doing aquaponics?

But it is something you could do ?

Maybe a little bit in the future. But it impresses me as a way to use water flow to grow lots of stuff in a permanent sort of way including plants and animals and fish.

I do question making it a recirculating system as some have done.

John

Comment by john Wed Mar 6 13:46:33 2013

You're tough to fool, Anna. And I bet you don't think the Elephant Man looks anything like an elephant either.

I've always questioned the advantage of aquaponics too: it requires more fresh water (possibly the least available limiting resource overall in food production) than planting in the ground and tanks take up space over the soil anyways, so you're not saving acreage.

Comment by doc Wed Mar 6 22:09:52 2013

We have an aquaponics system that doesn't use any of these electrical components except a pump. the pump takes the water from the pond into the grow beds, and automatic siphons pull it down a waterfall back into the pond on a 20 minute cycle. the pump costs less to run in a month than a light bulb. we don't heat the water; in zone 7, there's no need. and as the system is outdoors, there are no lights involved. we do feed the fish, as we are still getting the system going, so there's a small fish-food cost, but that's very minor. our AP system is designed to produce fresh greens for our table, as well as fresh fish; both are a primary goal. (we're getting bluegill, though, not tilapia; they are native and taste better.)

Here's our system: http://sunflowerriver.org/blog/overview-of-the-pond-our-aquaponics-system/

Comment by yarrow Thu Mar 7 13:50:05 2013
After several years researching aquaponics and building several experimental systems, I came to much the same conclusions you have. The method really appealed to me as a way to produce safe fish to eat in a dangerously polluted world with declining natural stocks. But since most fish food is made from wild caught fish, it is still very much a part of the natural system. I mean this both in terms of the threat of chemical contaminants such as mercury and PCBs that accumulate in top predators, and in the impact of overfishing causing species loss. It really doesn't matter if you remove one large fish or the equivilent weight of tiny ones from an ecosystem, the impact is the same. It is possible to build a very efficient system, that makes the energy cost worthwhile, and I believe that insects can be farmed as a sustainable source of protien for fish food. But a lot of work needs to be done in these areas before aquaponics makes sense on any siginficant scale.
Comment by Joe Thu Mar 7 16:15:42 2013
Yarrow --- That's an interesting system --- I like the use of the grow area for starting transplants for the garden. I hope you'll drop back by and let us know how it does as you go into year two.
Comment by anna Fri Mar 8 13:29:08 2013

That bottom photo is the backyard of a local bloke I know, here in Australia! In fact, looking at the photo closer, I actually took it! It looks like you got it from somewhere else, but I'm totally fine with you using it Anna. How weird is it that my photo would unknowingly show up on a friend's blog!?

Check out my page here for more photos of John's setup: http://green-change.com/2009/03/31/backyard-aquaponics-in-gerringong/

My biggest issue with aquaponics is that the systems don't seem to be terribly resilient. Things like water quality issues (pH, salinity, temperature), power outages, mechanical failures, fish diseases, etc can quickly wipe out the system. It's fine as a hobby, but it's not for everyone. I do think that it could work really well on a commercial scale, though, as long as the energy costs aren't too great.

@doc: Aquaponics actually uses a lot less water than planting in the ground - your only water losses are from transpiration and evaporation (plus what's stored in the plants as they grow, I guess). The water is just circulating around and around. Also it can be more space-efficient, since you can stack the grow beds on top of the fish tanks. You can also pack the plants closer than traditional in-ground methods (a bit like square foot gardening), since they aren't competing for water and nutrients.

Comment by Darren (Green Change) Wed Apr 3 08:38:36 2013
Darren --- That is so weird! If you click on the picture, you'll go to Aquaponics Australia, which is where I found it. It was the best-looking, DIY-type aquaponics photo I found on the web.... :-)
Comment by anna Wed Apr 3 09:07:33 2013