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Greenwater Aquaculture - low energy, high output

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posted 12 years ago

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Greenwater Aquaculture is basically the process of growing algae and algae-eating fish together in a recirculating aquaculture system (RAS). I've seen a few papers from some UVI systems that look very promising for fish production in terms of energy.

Based on their information, we should be able to produce over 130kg (300 lbs) of fish a year with 10 watt (pump and aeration). This requires a 40 watt solar system in my climate. The idea is to move the water slowly through the filter to let the solids and dead algae drop out, then return to the main aerated tank. That saves a lot of energy.

Here's an example system:
4000L Fish tank (swimming pool)
200-400L clarifier (200L drums, basic baffles for solids removal)
500 lph pump (or less) - easily done with airlift
5-10 watts of aeration (2 small aquaium air pumps)
stocking rate of 13kg/m3 (total biomass 52kg, yearly production 100-150kg)

It will only work with algae eaters, like tilapia and some types of carp. The algae serve as food (small portion) and biofilters.

Solids need to be removed daily from the clarifier, so I was thinking maybe mixing with bedding for earthworms, maybe BSFL, or some garden beds. What else could the solids be used for (methane?)?

Here's a discussion that has a lot of details:
http://www.aquaponicshq.com/forums/showthread.php/3522-Greenwater-Aquaculture

I am interested in the fish component, but I think a system like this could have a hydroponic, wicking bed, or regular garden component, too. Just route some of the water to your grow beds every week.

These systems are cheap to build. You need a fish tank (4 x IBC, or swimming pool), a few 200L drums (1/2 IBC), a small pump (or airlift, 300-500lph), and a small air pump with stones. I could see a 4000L system being built for $600 or less, including the solar system to run it (10 watts an hour demand, 50 watt solar panel with battery, controls, inverter, etc).

How many $600 systems do you know that can produce 150kg of fish a year and are completely solar powered?

You need a water pump that won't mind the algae, and an airlift is perfect for this. These pumps aerate and pump water at the same time. You make one with some PVC and a small air pump. Here's an example: http://www.backyardaquaponics.com/forum/viewtopic.php?f=18&t=11703&start=15#p314124

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Chris Kott

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posted 12 years ago

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Hi Abe,

Thanks for all the info. My grandmother has a pool that wasn't opened in the last couple of years, so I'm going to see if we can go the aquaculture route. I have not yet perused the link you posted, but believe me, I shall. My question is this: why wouldn't you set up the pool as a many layered polyculture, with living things occupying every niche? Operating outside, you will likely host a host of critters you didn't intend on feeding, and you may even have pest problems as a result. I am taking all of this from other gardening/systems situations where permaculture was the ultimate answer, I figure that a lot is transferrable. For instance, you would likely end up with some sort of solid waste accumulating in your baffle barrels, but what if you introduced a bottom-feeder, a small species like brown bullhead (small brown catfish that we find in muddy water in Ontario, colloquially known in parts of Ottawa Valley as mudpout) for instance, to eat all the algae-eater poo? My point is, and I will try it when I get to experimenting, that you could end up with a situation where you are harvesting not one, not two, but multiple species of edible food from your pond, as opposed to having one farmed species (and I apologise, but what you are describing with one species of fish eating algae is aquaponics, not aquaculture, especially if you separate the solid waste from the water mechanically and then add it to a garden system or what have you, even the wicking lines, which I personally think are a great idea, puts your specific description in the realm of aquaponics).

I would love to see this thread develop, so please accept my criticism in the constructive spirit in which it was meant. There is nothing inherently wrong with aquaponics, just that a little more planning in the beginning stages makes for much less input after you set it all up, which accords with the larger idea of permaculture, am I right?

-CK

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Chris Kott

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Hi again,

I forgot something that occurred to me while reading your post. I've seen floating platforms made out of that rigid styrofoam insulation used as hydroponic rafts floating atop aquaculture and the filter stages of aquaponics, usually used to grow greens. This might be useful to you, perhaps in your filter baffle, though if you try to apply it to the pond surface, you may negatively impact algae growth. I was also wondering if there was anything about providing fish feed in any quantity, as in paddock shift systems where you make sure feed is available so when the forage is insufficient, you know when to shift.

-CK

Abe Connally

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Well, it's not really aquaponics, because it doesn't have the hydroponic component. Although a hydroponic component could be added, you would not want it fully integrated, like in aquaponics, because of the algae. Adding a hydroponic system in loop with the aquaculture would reduce it's efficiency, and you would have better production with separate, but linked, systems.

The problem with polycultures in intensive aquaculture is do to the limiting agent, dissolved oxygen. There is only so much O2 to go around, and often, there is plenty of feed. So, optimizing the feed won't gain you much in terms of production, because you will still be limited by O2. It would be tricky to set up a polyculture in a small system, but it could be possible, especially with some carp species.

The waste in the barrels must be removed daily to avoid O2 depletion in the system for decomposition of the wastes. You could easily drain that into a separate tank, though and feed prawn, or other species (duckweed, etc). In my system, I will use that waste to irrigate plants in a wicking bed.

Usually, the daily feed rate is around 1-2% of the weight of the fish. In these systems, you have a feed conversion ratio of about 1.2-1.6. That's 1.2 units of feed in, 1 unit of live weight out.

The point of this post was how we can optimize the aquaculture component in terms of energy. Basically, the Greenwater system should out perform an intensive RAS or aquaponics system in pounds of fish/food per watt of energy used. If you want to go the route of aquaponics, you are looking at less than 1/2 the food production for the same amount of energy.

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Chris Kott

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I'm sorry, Abe, but I disagree with your definition of aquaculture. The wicking feed to your garden, because part of the pond resources are being routed out of the pond, constitutes a drain on the pond system, whatever is being produced in the garden. Yes, the waste products are fertilizing the garden, but the produce of the garden aren't going towards increasing the yield of the pond system, right?. It necessitates an input, though I am at a loss to explain how even aquaculture could work without even one pump. I am fully prepared to admit it is a matter of semantics, however, because I like the idea of growing fish for food. For the record, though, I was taught that the distinction between aquaponics and aquaculture was that there was one system, not two running parallel, and that there were no identifiable waste products within the one system because elements within that single system were using each other's waste products as a food source. But again, it doesn't invalidate what you're doing, it's just that I disagree with your use of the word aquaculture for this specific example. Factual due diligence done...

I am curious as to why you wouldn't employ a pump to oxygenate the water, either with a bubbler, or by elevating the height of a part of the system, say a baffle filter or two to roof level, positioned to allow water to fall from a height, possibly even through a shower head to maximize oxygenisation. My efforts will lean towards polyculture, but I would think that you would prioritize adding dissolved oxygen with whatever energy inputs you are adding. Also, while I agree that the more complex a system, the more that can go wrong, I don't see the difficulty in adding a bottom-feeder to eat the carp or tilapia's crap, even if you would need a screen mid-way down to keep the two species separate. Also, if you don't mind having a tank large enough for the purpose, couldn't you use another large tank into which you would pump your vegetarian fish's crap to feed the catfish, and in that same tank grow something that either fish or humans would eat?

Thanks, by the way. The numbers and setup will be very useful however my specific setup will differ.

-CK

Abe Connally

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posted 12 years ago

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Yeah, aquaponics would be running one system, aquaculture would be the running of 2 systems parallel (aquaculture and hydroponics). but, even aquaponics has waste products, especially if they are stocking at even 1/2 the densities we are talking about. Solids become too much for the aquaponics system to manage, and must be removed with a solids filter. Technically, aquaponics is a type of aquaculture, but I think you are concentrating on the wrong thing here. This is aquaculture, as we are raising fish without a plant component (plant component is not necessary for fish system).

The water from the hydroponic/wicking bed component would NOT return to the aquaculture unit. It is not a loop, so the plants are not part of the filter, like in an aquaponics system. This is definitely an aquaculture system, just like a recirculating aquaculture system that uses bacteria in a biofilter to help break down wastes, but we are using algae instead. And the waste will consist of dead algae, fish poop, waste feed, etc. that will be removed from the system.

The system does use a pump, an airlift pump. It pulls 5 watts and pumps 320 gallons an hour. We also use another air pump for added aeration. We don't use regular water pumps, because they are extremely inefficient (see if you can find a water pump that does 300 gph on 5 watts). Air pumps and algae will produce enough O2 for the stocking density we are suggesting.

The point about polyculture is that feed is not the limiting agent, O2 is, and will always be. Adding multiple species does nothing to address your limiting agent. Sure, you can add more O2, but you have a maximum of O2 that can be put into the water (saturation). So again, O2 is your limit, not feed or waste, so every fish and/or animal needs to be producing the most food for the O2 that you have.

If I add a bottom feeder to the system, he is taking O2 away from the more productive fish. He also cannot remove the waste fast enough. That is why mechanical filtration is used. It is more efficient and does not require extra O2. This is not a pond, this is an intensive system.

Any increase in height in the system requires more energy. So, if you add a few inches, you will have to add more watts. This layout is designed to use 10 watts of electricity 24/7, which would require a 40 watt solar system (about $400).

If you think you can produce more fish (yearly production of 100-150kg) for 10 watts, please show us how that is done. As far as I know, this is the most efficient intensive fish production system ever proposed. I posted as an example of what can be done with little energy.

Most aquaponics and aquaculture systems require a lot of energy to run, and are not really viable for an off-grid system. Look at the power ratings of the pumps, and how much fish they ACTUALLY produce (not their theoretical maximum). For similar production rates as mine, you are looking at using 50-100 watts 24/7 using normal methods.

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Chris Kott

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Thanks Abe,

I still think we're not understanding eachother. Firstly, I believe you have defined aquaculture inaccurately. Aquaculture is an integrated system (one single, whole, all-encompassing water system) that mimics or uses natural life systems and species' relationships to achieve the desired effect. By definition, aquaponics is an artificially supported system. Lets be clear here: I am not trashing your system. I am not trashing aquaponics. But the first is closer to natural systems than the second. Aquaponics is what you do in tanks with tubing and hoses, filters and pumps, doing everything but growing the algae mechanically; aquaculture is what you do when you design a pond system that works. With aquaponics, if the human running the system disappears for a while, the system stops and everything dies. With aquaculture, everything is designed to support everything else, so that when the human who set up the system is away doing other things, everything continues whatever the human does. Aren't there inherently higher efficiencies when you get living organisms to do the work either you or some piece of power-gobbling machinery otherwise has to do?

This discussion almost belongs in its own thread. If you don't believe what I'm saying, I can find links to reputable sources. Or PM Paul, and ask him to define the two terms.

If you read my previous posts, you will notice that no where did I suggest that the water being wicked away into the garden was returning to the pond. I actually commented on the fact that because resources are leaving the system, apart from the harvested fish, it is aquaponics rather than aquaculture. I might be stretching the meaning of aquaponics, as there are no plants being raised in water for harvest, but the only difference in what you describe is the fact that the medium your plants are growing in is your garden soil.

I will leave, for the moment, the idea that you might be leaving out of your system life forms that oxygenate the water. My research in this specific area is incomplete. But let me ask you this: if your system is running on solar, or any other renewable, and you spend the money on infrastructure once, then what difference does it make how much energy you are taking out of the wind/sun? It makes a definite difference if your power is derived from non-renewables, or a feedstock that you need to manage, but until the sun goes out, there is no cost to you beyond the size of the initial investment.

I do understand the idea that oxygen is the limiting factor. That's just one of those things that is so obvious it's almost insulting to keep plugging. Let's not.

I even concede that depending on the size of the system, it might be wise to have discrete areas within the pond, such that the waste sediment gathers in one area, where the bottom-feeders eat. Just to sum up my point, I think that the benefits to the integrity of the system warrant adding more oxygen to it, and if that means capturing more renewable energy, I would judge it worth the added initial cost. Is that not reasonable?

-CK

duane hennon

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posted 12 years ago

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Abe,

have you considered a separator screen on your airlift to divert the solid out? this would remove the solids out of the water column automatically and reduce the oxygen loading from the clarifier. the screen wouldn't remove everything but diverting a large portion, especially if your loading your system, would be helpful. this could be in-line so no extra pumping would be needed

water with solids -> airlift -> screen - -> clarifier ->
i
-> solids -> disposal

Abe Connally

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the screen would tend to get blocked up very fast, as the water is full of algae. Putting a mesh after the clarifier would prevent solids from re-entering the system, and could possibly work, if you cleaned it daily.

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Abe Connally

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Chris Kott wrote:Firstly, I believe you have defined aquaculture inaccurately. Aquaculture is an integrated system (one single, whole, all-encompassing water system) that mimics or uses natural life systems and species' relationships to achieve the desired effect.

Aquaculture is raising species in water, nothing more. It has nothing to do with mimicing natural systems (though, that is more desirable). There are many, many aquaculture systems that are basically just big tanks with a filter (completely unnatural). No one calls them aquaponics systems, because they don't have the "ponics" part. There are also natural aquaculture systems that mimic nature, etc, but that is not a requirement of aquaculture.

Chris Kott wrote:By definition, aquaponics is an artificially supported system.

By definition, aquaponics is the combination of aquaculture and hydroponics. It can be artificial or natural. These systems are made to use plant growing systems to filter the water, instead of the normal mechanical and/or biofilters used in aquaculture.

Chris Kott wrote:Aquaponics is what you do in tanks with tubing and hoses, filters and pumps, doing everything but growing the algae mechanically; aquaculture is what you do when you design a pond system that works. With aquaponics, if the human running the system disappears for a while, the system stops and everything dies. With aquaculture, everything is designed to support everything else, so that when the human who set up the system is away doing other things, everything continues whatever the human does.

There are intensive and extensive aquaculture systems. Commercial aquaculture is usually intensive, and it depends exclusively on pumps, energy, humans, etc. Extensive systems are more resilient, and an example would be a natural pond. They also have drastically reduced yields (1-2kg/m3 vs 10-30kg/m3 of intensive systems).

Chris Kott wrote:Aren't there inherently higher efficiencies when you get living organisms to do the work either you or some piece of power-gobbling machinery otherwise has to do?

it depends on the particular system, and how efficient those organisms are. It would take a lot of bottom feeders to compete with a barrel filter in terms of filtration efficiency. Sometimes, adding additional organisms reduces efficiencies (as in this system). It depends on what the limiting agent of the system is. In aquaculture, the limiting agent is usually O2, so adding any species that consume O2 is only beneficial if they significantly increase yields. Most fish are not as efficient at converting food and O2 to meat as tilapia, therefore, adding them into the system reduces the efficiency.

Chris Kott wrote:This discussion almost belongs in its own thread. If you don't believe what I'm saying, I can find links to reputable sources. Or PM Paul, and ask him to define the two terms.

it's easy to look up the definition and examples of both systems. I am very familiar with both systems, as I have been involved with this sort of stuff for over a decade. Again, aquaponics is aquaculture (the aqua part) and hydroponics (the ponics part) combined. Aquaponics is a form of aquaculture (farming in water). If you have a link to something that disputes that, please post it.

Chris Kott wrote:If you read my previous posts, you will notice that no where did I suggest that the water being wicked away into the garden was returning to the pond. I actually commented on the fact that because resources are leaving the system, apart from the harvested fish, it is aquaponics rather than aquaculture. I might be stretching the meaning of aquaponics, as there are no plants being raised in water for harvest, but the only difference in what you describe is the fact that the medium your plants are growing in is your garden soil.

Most aquaponics systems recirculate the water from the plants back to the fish (as part of the filtration system), so I don't understand how taking water out of a aquaculture system to a land based plant systems constitutes aquaponics. Taking water out to a wicking bed is significantly different than most aquaponics systems.

Chris Kott wrote:I will leave, for the moment, the idea that you might be leaving out of your system life forms that oxygenate the water.

the algae oxygenates the water, so we are including those species. But, very few species produce O2 at rates that can compete with mechanical aeration.

Chris Kott wrote:My research in this specific area is incomplete. But let me ask you this: if your system is running on solar, or any other renewable, and you spend the money on infrastructure once, then what difference does it make how much energy you are taking out of the wind/sun? It makes a definite difference if your power is derived from non-renewables, or a feedstock that you need to manage, but until the sun goes out, there is no cost to you beyond the size of the initial investment.

It makes a big difference in the size of power system required (setup cost and return on investment). If you can grow 100 kg on 10 watts rather than 50 watts, you've just cut your power system cost and ROI by 80%. To setup a 10 watt system, you are looking at $400 in a power system. To do 50 watts, you are looking $2000 power system. It is a big difference, and if both systems produce similar yields, then the 10 watt system just saved you a lot of time and money.

Chris Kott wrote:I even concede that depending on the size of the system, it might be wise to have discrete areas within the pond, such that the waste sediment gathers in one area, where the bottom-feeders eat. Just to sum up my point, I think that the benefits to the integrity of the system warrant adding more oxygen to it, and if that means capturing more renewable energy, I would judge it worth the added initial cost. Is that not reasonable?

Not really. It depends completely on how much more production can be gained by adding more species to a system. If I can yield 120 kg on 10 watts, or add a few bottom feeders and another 5 watts of aeration for them, that is now 15 watts, and I probably only gain 10kg of production (at most, because those bottom feeders won't use the O2 as efficiently as tilapia). Leaving waste in the system is not an option, because it drastically reduces the O2 levels (limits production). Waste must be removed as fast as possible, that is the reason for the mechanical filtration. It would take a lot of bottom feeders to match the efficiency of the filtration. Adding additional O2 demands that can't clean the water as fast as the clarifier do nothing to increase the efficiency, and they reduce the yields of this system.

I don't think you understand the system and how it works. Solids are removed constantly, and the water must be aerated constantly to support the levels of fish we are talking about. Adding additional fish to the system requires more aeration, or lower stocking rates of other fish. This is an intensive aquaculture system. It works at a much higher stocking density than a pond.

I suggest everyone go read the links and details provided in my original post to better understand how the systems work, and why it is set up this way. This is by far the most productive aquaculture system in terms of yield vs energy use for the size of the tank (1,000 gallons, 150kg of fish a year, on 10 watts).

If anyone can find a working system that is more efficient in terms of kg per watt with the same or better stocking densities, please post them here. I welcome any and all examples of systems that have demonstrated a higher efficiency using less energy.

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Chris Kott

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posted 12 years ago

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Thanks Abe,

After you break it down like that, I admit I am seeing more of the picture than previously. I guess that some places that discuss aquaculture from a natural or permacultural perspective might use terms differently. I can't seem to find the article I was reading wherein the arguments I presented were sourced, but your definition of terms accords with the way I originally understood them. If my approach was antagonistic, or even just annoying, I apologise. To irritate was not my intent.

I am still looking over the material you linked to. I was wondering what, if any, pest or disease problems you might encounter and how you handle them, or is it a problem at all?

-CK

Abe Connally

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Chris, I'm glad your seeing what I was trying to say.

Pests in some areas pose a small issue (mostly birds), and disease comes into play when the fish are stressed. For Tilapia, that means when temperatures drop. So, if your ground temps are lower than 70F, you need to work on a greenhouse or some sort of climate control. The other option is to select native species that can deal with the local climate.

Here's an example university system that can gives you loads of math to play with:
http://procs.gcfi.org/pdf/gcfi_51-25.pdf

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duane hennon

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Abe,

you could use a screen shaped like a half pipe 90 degree offset
the airlift dumps into the screen, the water passes thru
the screen is higher on one end, the lower end attached to a flange or pipe thread outlet
by setting the levels, the solids will slide to the lower end to flow out either continuouly or can be valved for periodic empting
removing solids as soon as possible further reduces O2 demand as they are gone before bacteria have a change to colonize them
I have built them

one of the advantages of greenwater systems is the reduced O2 demand
this is from several factors
1. algae has the ability to use ammonia directly
2. this reduces the need for nitrite/nitrate bacteria which consumes a lot of O2
3. depending upon lighting, algae both comsume and produce O2
4. a properly set-up system would have algae as O2 positive or at least neutral while eliminating ammonia

to me at least, it just make sense that you want to save your limiting resource, O2, for your most wanted product, fish, not bacteria.

Abe Connally

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duane, could you post a photo or sketch of what you are describing? I think I get the concept, but I would like to see how it is done. How fine of a mesh are we talking about?

I am thinking I may put the airlift after the clarifier, to pull things through the system and give the water a good blast of air right before it gets back to the fish. I'll probably employ a solids lifting overflow to move water from the fish tank to the clarifier, and if I could screen some solids out along the way, that would definitely help.

For the clarifier, I had planned to have it dump 1-2 times a day, preferably during the night, when the O2 demand will be the greatest. I can see where a self-emptying screen mechanism would help a lot with O2 demand.

Algae can also be a food supplement for some species.

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Chris Kott

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Ooohhh, data! Scads and scads of data! Thanks Abe. I was also wondering if there are any crops that you could turn into fish feed, crops that you might water with the wicking lines and fertilize with the solids. Or, if the fish species in question was omnivorous enough to eat insects, could they be trapped and fed to the fish? I suppose it depends on the fish species. The list of data on farmed species will prove very interesting, thanks again.

Sorry, I tend to babble. I was actually looking for information on aquaculture before finding this post. Thanks for helping me clear up some messy reasoning.

-CK

Abe Connally

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yeah, I'm an info junkie, too. There is a lot more information in that thread I linked to in my original post.

I think you could mix the waste from the filter with shredded paper or cardboard and give it to worms or BSF. both would be good fish food. Hanging a bug zapper or light over the tank would help harvest some insects at night.

The wicking beds could support all sorts of stuff, and by my calculations, this 1000 gallon (4000L) system could water 70 square feet of wicking beds in my climate. So, yeah, I think raising some fish food would be possible. If you are aiming to max out production at 150 kg a year, you would need about 225 kg of fish food (1.5 FCR) at around 35% protein.

For feeding fish, I hope to incorporate some of my other waste streams from rabbits, pigs, and ducks. I know if I grind up slaughter wastes and mix them with stuff (veggies, earthworms, BSF, flours, etc), I can make my own high protein pellets. Some of the manures from these other things can be fed to fish or be used to grow duckweed.

For algae systems, your options on fish are limited. You want fish that can eat algae and have low O2 demands. Tilapia and some species of carp would work well, but I think yellow perch might work, too.

If you are interested in low energy aquaculture, check out the following:
http://www.backyardaquaponics.com/forum/viewtopic.php?f=1&t=11704
http://www.aquaponicshq.com/forums/showthread.php/6994-Low-Energy-Aquaponics-LEAP
http://www.aquaponicshq.com/forums/showthread.php/3522-Greenwater-Aquaculture

Lots of cool ideas are explored in those threads, and they are loaded with data and helpful tools.

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Thanks Abe! It's gonna take me a while to work through everything, but this puts me miles ahead of where I was. As to fish species, I'm living in Ontario, Toronto now, but looking at property in the short to medium term as far north as New Liskeard, so I obviously have some research to do in terms of applicable native species if it is something that is going to overwinter well. These definitely don't qualify as native, but I read about a species of Pacific Salmon, sockeye or something I think, that was said to eat algae until it migrates to saltwater, and that landlocked populations have been found that had adapted to an algae-eating freshwater environment as adults. Does any of this sound familiar? Based on what you know on the subject, does it sound plausible, or are salmon a different kettle of fish entirely? (sorry, I couldn't resist

)

-CK

Abe Connally

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posted 12 years ago

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sorry, I know nothing of salmon, except that they taste great with butter.

Alternatively, go with a simple recirculating aquaculture system, probably around 50-60 kgs/yr (tilapia) from 10 watts: http://www.aquaponicshq.com/forums/showthread.php/6994-Low-Energy-Aquaponics-LEAP?p=42061&viewfull=1#post42061
With that, you could run whatever species you want, and you don't have to deal with algae, but you get lower production for the energy input.

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Chris Kott

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Yes, salmon does taste great. It is turned quite easily into my favourite kind of sashimi. I like the low-energy, high-output idea. Have you seen anything about greenwater aquaculture being used to grow feeder fish to feed a fish like salmon, or another fish-eater? Tilapia might do well in such a system, but I think they'd taste better after being converted to salmon meat

. Seriously, though, I realise the conversion rate would be large (I seem to remember a ballpark figure of 2 to 1, feeder fish to salmon, though it could have been inflated), but that approach could make species too small for human consumption (I'm thinking of a species of Mountain Minnow that has been brought up in other threads) useful in ways other than making shitty water.

Adding all these ideas and variables takes us way away from the original point of this thread, but I think anything you add that draws on your experience is a priceless addition, and any good ideas about the placement of greenwater aquaculture and its creative application in a farm or homesteading system makes this brilliant approach even more valuable.

-CK

Abe Connally

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yeah, that might work, raise a bunch during the warm months, then freeze them and give them out to the salmon over the year. Find a feeder fish that eats algae and occupies stagnant water.

Even if it is 2:1 conversion for that, and 1.5:1 for tilapia, you are coming out at 3:1 overall, which is on par with chicken. And salmon tastes way better than chicken...

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Well at least I'm not completely out to lunch on this one. I think it was your post earlier that mentioned using a greenhouse for cold weather operation. I like that idea. It applies well in those areas of the north that aren't warmed by well-timed seasonal winds and warm ocean currents.

-CK

duane hennon

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hi Abe,

i spent last night looking for my files (from the early 90's) on fish. i haven't been able to locate. at about 3 AM this morning it hit me. instead of my design, why not use something already there. a gutter guard. if your airlift would dump onto a piece of rain gutter with a guard, the solids would be removed and the water collected in the gutter to flow to the next stage. I might take some investigation as to which is the best, but i think it would be worth it. even some window screen supported on the gutter may work

http://www.guttersupply.com/p-gutter-leaf-guards.gstml

good luck

Chris Kott

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This might be obvious, but by running your dirty water (to the filter) over a gutter guard, wouldn't you be greatly increasing the amount of oxygen by increasing the surface area of the water? At the right flow rate, over a screen with holes the right size, wouldn't the water separate into droplets as it gets filtered?

-CK

Abe Connally

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yeah, it could help with aeration a bit. A gutter guard is a good idea.

I would worry about splashing wasting the water, but maybe something could be figured out. Thanks, duane!

The trick will be to figure out a situation where this doesn't add a lot of height to the filter configuration. In terms of energy, we are trying to keep things around 4-5 inches of head or less (less is better).

So, what I am thinking is a solids lifting overflow to a gutter guard/screen, that then goes through a clarifier, then the airlift raises it back up to the fish tank. What do you think?

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Chris Kott

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Just curious, Abe. How is losing water through wicking lines any different from losing water to splashing with regards to its effect on the system? Also, as to that splashing, what you require of it regarding minimal head works to your advantage in that respect. Also adjusting the flow rate and perhaps using a woven wicking membrane (something to bridge the drop to the gutter guard) to control splashing, or that same type of membrane, just a scrap of it where the flow hits the guard in case of splashing.

I'm long-winded, but my point is that these are things that can be addressed, and without increasing the energy cost of the system, unless I miss my guess. Although putting it together with the description at the end of your last post regarding specific setup, my earlier solutions might not fit.

-CK

Abe Connally

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loosing water to splashing is a waste, whereas taking water for wicking beds produces food. I am sure it can be done without wasting water, it's just the first thing I thought of. I don't think it is a major obstacle.

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John Sizemore

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Un Scientific experience.
I started out with 8 tilapia caught from a river in a small garden pool. About six month later I moved them two 12X3 above ground swimming pool on the roof of the house I rented. When I moved back to the United States 18 months later I was giving fish away by the dozens. When I shut it all down and gave my fish and pumps to my best friend we lost count at 2000 tilapia. The only food they were given were some table scraps. Tilapia filters algae out of the water down to three microns.
They need some kind of control on population such as peacock bass or even large mouth bass to keep numbers down. Better yet, net out a good portion and use for chicken feed. A female breeds every six weeks and they put out hundreds of babies per cycle. The breed at three months of age or so.
One gallon of water can produce one pound of fish every four months. Stocking rate is irrelevant if you put in some predators after three or four months and let them stock themselves. Whether you want them to or not they will overstock themselves.
Lastly when I move back I will have tilapia in my farmstead as one of the central protein sources. So I am not at all negative about them.
In aquaponics the waste is ready to use fish effluent for fertilizer or better yet as hydroponic solution for heavy fruiters that don’t really like aquaponics. When I had my aquaponics system I just dumped the water from my clarifier on my banana plants. Bananas are heavy feeds that need the organic matter or they will wear out the land in about three years.
To separate the solids I used a plastic barrel with a flower pot upside down inside. I had my water come in at the bottom and flow up through gravel over the flower pot. Then the water flow out a discharge tube near the top. Once a day I purged five gallons or so of slime out of the filer from the bottom. It served as both a biofilter and a clarifier.
As far as usability, aquponics is not that power intensive but it needs to be constant. That is the weakness in an off gird situation. I was in an area with multiple black outs per day. On another forum I am approaching Stirling engines and bio digesters as a means for off grid production. One hundred watts of power can easily produce 500 pounds of fish per week and a ton of vegetable material in the same period. I am not saying crops I am saying leaves, roots and all.

I am the first generation of my family to grow up on the grid eating out of the super market. I hope to be the last.

Abe Connally

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John, what was your energy requirement for that pool that went crazy with Tilapia? One gallon of water for one pound of fish every 4 months, but what is the energy requirement for this kind of production rate? What was the water flow (liters per minute or hour or whatever) of your filtration system? Did you have some air stones going, too?

For population control, you can breed hybrids (male from one species, female from another), and get sterile offspring. So, you keep a few breeders in a small tank to supply you with a bunch of sterile ones to grow out.

I kinda like the idea of them breeding out of control, because it is food for chickens, ducks, and pigs. The problem with that, however, is that it is harder to manage with a limited energy system.

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Abe, do you have any information available comparing the costs and efficiencies of different renewable energy sources? I was thinking specifically of the traditional wind-powered water pump. All I'm thinking is that if you had a water tower to act in the same way as a mill pond, when the wind was blowing, it would fill the tank, which would dump either at specific times or at regular intervals, and more regularly at night when O2 demands are highest (if I read what you posted right). The tower would have an overflow directed to pour into the tank, and if the solids were screened out before the water was lifted to the tower, it could be used as a tank for growing algae on its own before flowing into the fish tank.

I am missing some numbers that would tell me if this would work at all, let alone if it makes sense. But parts of this idea have been used separately to irrigate for over a century and to operate mills on-demand before electricity had even been thought of. I thought that if it were possible to move water without using electricity, and without the conversion losses inherent in generating electricity from wind, perhaps this would be an option for those with 1)varying elevations on a larger property 2)useable wind.
I am trying to find an old-style wind-powered water pump for purposes of pricing. Has anyone seen this done anywhere?

-CK

John Sizemore

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I had a 100 watt 3500 gal an hour fountain pump. Like I said I was playing with it. For my filter I have a 55 gallon plastic drum that I had the water flowing up from the bottom and out the top. I purged the filter from a bottom drain every day.

Mike Sipe put out a hatchery manual on the internet that told all about tilapia few years ago. It was free. Now he supplies it with purchases but you can still find websites that offer the old manual for free since it was a freebee in the past.
I was not really doing anything beyond playing as I was working as a contractor and could not baby sit the system. I just observed and found that the information I got from other sources all panned out.

I am the first generation of my family to grow up on the grid eating out of the super market. I hope to be the last.

Abe Connally

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Chris Kott wrote:Abe, do you have any information available comparing the costs and efficiencies of different renewable energy sources? I was thinking specifically of the traditional wind-powered water pump. All I'm thinking is that if you had a water tower to act in the same way as a mill pond, when the wind was blowing, it would fill the tank, which would dump either at specific times or at regular intervals, and more regularly at night when O2 demands are highest (if I read what you posted right). The tower would have an overflow directed to pour into the tank, and if the solids were screened out before the water was lifted to the tower, it could be used as a tank for growing algae on its own before flowing into the fish tank.

I am missing some numbers that would tell me if this would work at all, let alone if it makes sense. But parts of this idea have been used separately to irrigate for over a century and to operate mills on-demand before electricity had even been thought of. I thought that if it were possible to move water without using electricity, and without the conversion losses inherent in generating electricity from wind, perhaps this would be an option for those with 1)varying elevations on a larger property 2)useable wind.
I am trying to find an old-style wind-powered water pump for purposes of pricing. Has anyone seen this done anywhere?

-CK

yeah, it would work, but you would need a huge tank to store up the water. For 5 watts of solar power, you can pump 320 gallons an hour, or about 7600 gallons a day. So, if you are running water from a windmill, and want enough for at least one day of no wind, then you need more than 7600 gallons of storage.

Electricity is far more efficient than moving water with the wind.

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Abe Connally

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John Sizemore wrote:I had a 100 watt 3500 gal an hour fountain pump. Like I said I was playing with it. For my filter I have a 55 gallon plastic drum that I had the water flowing up from the bottom and out the top. I purged the filter from a bottom drain every day.

Mike Sipe put out a hatchery manual on the internet that told all about tilapia few years ago. It was free. Now he supplies it with purchases but you can still find websites that offer the old manual for free since it was a freebee in the past.
I was not really doing anything beyond playing as I was working as a contractor and could not baby sit the system. I just observed and found that the information I got from other sources all panned out.

The important thing is that it worked, and that's what counts. If we could all have something that worked as well as yours we'd be doing fine.

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Roger Gietzen

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posted 8 years ago

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Abe,

The links to the aquaponicshq.com site are down. Maybe you can get me started in the right direction. I am developing a community farm in Haiti, which is off grid. On the property is an above ground cement 5000 gallon water tank which is currently not in use. I'd love to get an aquaculture system set up for the locals to grow their own food, but the high energy ones are not feasible. Do you have some drawings so I can better understand how your system works or another link? If you wish, you can email me directly. rgietz at hotmail dot com.

Sincerely,
Roger

Tobias Ber

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posted 8 years ago

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hey roger,
welcome to the forums.

did you see this ebook: http://www.backyardaquaponics.com/Travis/IBCofAquaponics1.pdf
it s a free download, maybe it helps a bit. but i m not sure if it covers that questions.

maybe you could ask at that site: www.backyardaquaponics.com/

best wishes for your project

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Roger Gietzen

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Thanks,

I'll check out those resources.

Take care

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