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Sylvia, convince me. Please :)  RSS feed

 
Chris Knipstein
Posts: 45
Location: Fort Wayne, Indiana
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I've read some websites and watched a lot of YouTube videos on aquaponics. I have even spoken briefly to a couple people who have done it, one who has made an attempt at commercially doing it. I love the idea of the system but something I haven't been able to get over in order to try it is, why? Just because it can be done, is it really the best way? My second concern has always been the back up system, it seems all can be lost so easily with a power outage.

I saw the aquaponics systems in the mid 80's for the first time at Disney's Epcot center in Florida as a teen and thought it was awesome. I always loved the idea of the symbiotic, efficiency of it all. But now I wonder if it's the best way. Is an integrated aquaponic system better than a separate aquaculture system, raising fish and filtering waste to be composted and fed into a soil based greenhouse? I've never read anything on filtering the waste out completely, rather than using it in an aquaponic system. Is it a difficult thing to do versus the aqauponic way? To me it seems there is a lot of time put into balancing an aquaponic system, and monitoring it to keep it balanced as fish grow and are removed and replaced by fry that don't put out anywhere near the same amount of waste. Where in soil you would have a more simple, baseline of nutrients from the soil, boosted and replaced by the composted fish waste. If I remember correctly, the version I saw at Epcot was meant as a demonstration of how food could be grown on a space station, fish in large tubes of water, plants grown in tubes where water was contained and misted over the roots and vacuumed out of the tube as needed. It made sense if you couldn't have soil it was a great system, but if you have soil is it still better?

Using 1/10th of the water I assume is compared to a traditional open air field irrigation system where the water is soaking deeply into the soil and the soil exposed to wind and direct sun between the rows. The growing medium used in aquaponics, with the marble like balls seems it would lead to a lot more evaporation from all that surface area versus a container of soil under the same surrounding conditions. I have thought about deep soil beds raised above equally wide and long tanks of fish would be the way to go. Creating a web of life in the soil, fed with the bi-products of the aquaculture system. I just can't imagine that the non-soil growing medium under a constant flooding and draining all day would use less water than a soil based system sitting next to it using a drip irrigation.

Seeing a short YouTube clip of yours I did love the idea of washing insects off of the plants and being able to plop them right back into the growing medium! Something that did pop into my mind that I had not thought of before seeing it was what about contamination? I know E Colli and some other such things are mostly feed lot or slaughter house problems, but if such a pathogen was introduced to an aquaponic system that wouldn't affect the fish could it live or even flourish in the system and contaminate plants if water was splashed onto them as fish were netted out of the tanks?

This is already longer than I hoped I could make it but finally, just how much back up do you need for the fish? It seems you could lose all your fish so easily is probably the one thing that has always kept me from trying anything with aquaponics. If I check the system at 8pm and the power was to be lost at 9pm without my knowledge, what sort of back up is needed to keep the fish from dying until they are checked on in the morning? Can bottled oxygen be enough if you were to lose power for a full 24 hours, or do you really need a back up generator system if you had an average greenhouse sized system? The one small commercial person I spoke to had a back up generator for the back up generator with tanked oxygen, and it made me think the back up system cost nearly as much as the rest of the set up. It seems lately multiple day power outages for some areas after large storms where I live are getting more and more frequent in the past few years.







 
Feidhlim Harty
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Posts: 163
Location: Ireland
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Hi Sylvia, I'm just hitching a lift here with Chris - interesting points raised and I'm curious to see your answers. I work as an environmental consultant in Ireland, designing reed beds, constructed wetland systems and willow filters. I'd love to try out a community based fish pond system, whether aquaponics or aquaculture, so I await your answer with interest.
 
Sylvia Bernstein
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Location: Boulder, CO
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Wow - that is quite a post! I think that in a nutshell you are asking why aquaponics vs soil and/or straight aquaculture, is the low water use real, is there a danger of pathogens, and what the need for backup power? Assuming I've got them all I'll attempt to address them one by one.

1) Why aquaponics vs soil and/or straight aquaculture? I'll start by saying that I love gardening in soil outdoors in the summer. I'm drinking my morning coffee looking out over my veggie garden as I write this. But aquaponic gardens have some distinct advantages, especially when done year-round indoors or in a greenhouse. First, there are no weeds. Second, aquaponic (and hydroponic) gardens can be significantly more productive than soil because the plants are being fed all the water, nutrients, and oxygen all the time. Third, the lack of dirt makes them cleaner for indoor growing, and helps to lower the harmful insect population. If you are in a greenhouse the mass of all that water helps to moderate temperature fluctuation. And, let's face it, the fish add a really fun, lively element to gardening.

As to why not just grow fish and use the waste water in your soil garden, I'll start by saying that myself, and my company, focus exclusively on home and school gardeners, not commercial farming. Most home food growers are unwilling to take on the expense and maintenance hassle of setting up a fully filtered aquaculture operation in order to grow game fish. What aquaponics does is provide that filtration for the fish system in a way that dramatically lowers the setup and maintenance cost and complication because it does it in a more natural way, mimicking a recirculating wetland environment.

2) Aquaponics uses far less water than traditional agriculture because the water is captured and recirculated, and is never drained off as it is in recirculating aquaculture and hydroponic operations. In our grow lab we find that our systems use about 1% of their water a day, so we need to top up the tanks about every two weeks or so. I'll compare those to my soil gardens where I'm running soaker hoses every day in the summer for 45 minutes. Granted, it is hotter and dryer outdoors, but the fact that the water is running off clearly plays a very significant role.

3) As for E Coli, and other dangerous pathogens, because fish are cold blooded creatures they cannot harbor those diseases themselves. The only way that could happen is if Salmonella were possibly introduced externally (a turtle getting into the system, or a bird flying overhead and dropping waste into the water). That said, I have never heard of someone getting any sort of food borne illness from an aquaponic system.

4) As you accurately pointed out, Aquaponic systems require power to circulate the water and provide oxygen to the fish. But the amount of buffer you have in a power outage depends on a couple of things. First, the type of fish you grow. If you are growing fish that come from a pond, or more still water environment like tilapia they will have far less need for high oxygen levels than, say, a trout that is used to being in a highly oxygenated environment. You might have hours to react, vs minutes. Second, the cooler your water is the more it will be able to retain the oxygen after the power goes out. That said, every aquaponic system should have some sort of backup plan for a power outage. We actually sell an inverter system called AquaBackup that runs off a marine battery that powers a DC aerator that ran for over three days when we first tested it.

I'll conclude by saying that I would never say that aquaponics is the end-all, be-all of gardening, nor would I recommend that anyone rip out their soil gardens and replace them with aquaponics. I do strongly believe that aquaponics is a wonderful addition to any garden, especially if you want to grow edible fish and/or you want to grow indoors, year-round.

Thank you for your excellent questions!
 
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