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  1. #1
    Members 15mules's Avatar
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    The benefits of Duckweed/ or lack of benefits???.

    Ok,
    I have read many post, not just here but in other AP places of how to raise duckweed and how to feed duck weed etc. But to be honest I am just not convinced of the benefits. I mean I understand it is renewable and sustainable and if that is your primary reason for feeding it, then I understand. I also have read of people feeding it as a "Treat" for their fish, and there again, if that is your primary goal I understand. But economically I just do not see the benefit.
    Here is the information I have gathered about duckweed. I have created averages from several different tests and studies I found, to simplify things and keep me from having to quote a bunch of different sources with fairly similar numbers.

    - Duckweed can multiply twice its original amount in 16 to 24 hours, under ideal conditions.
    - Duckweed has approx. 35% to 40% protein if grown under ideal conditions. (This is dry weight protein)
    - Duckweed has approx 5% to 15% fiber (this is based on feeding entire plant, leaves, stems, everything)
    - Duckweed is approx. 90% to 93% water (as are most aquatic plants)

    Now lets do some simple math with the above numbers.

    10 pounds of duckweed produced, would equal approx. 1 pound in dry weight once you remove the 90% water. This would mean for every 10 pounds of duckweed I could grow I would be producing the equivalent of 1 pound of dry feed with a protein of approx 35% to 43%.
    To produce this 10 pounds, I would need to provide a container (pool, plastic tub, etc) possibly piping to and from my AP system and possibly a pump to circulate the water.
    Floating catfish food in my area runs around $22.00 to $25.00 per 50# bag. That is approx .50 cents per pound, for 1 pound of fish food in the 35% to 38% protein range, basically the same as our 10 pounds of duckweed. My conclusion is; I worked for a week checking my duckweed, I invested in a container, maybe a pump and some pipe and my return on this is .50 cents worth of feed per week?? by feeding it "fresh", I am also risking spreading it to my entire system, and into places, I may not really want it! All this, for .50 cents of feed?
    Now look, I am certainly no expert on Duckweed. I have never grown or fed Duckweed. I am only going by the information I have gathered in the discussions on AP forums etc. as to how people are feeding and using duckweed and by the studies I have looked up where they have done test to determine the protein content etc. for duckweed. Maybe I am totally wrong about this? Hopefully I am. I would love to find out that Duckweed is truly a FREE Tilapia feed? If some of my findings is wrong, please explain it to me and help me see the benefit of duckweed.
    thanks for listening
    Never show your ignorance, by thinking you know it all

  2. #2
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    Re: The benefits of Duckweed/ or lack of benefits???.

    most people don't think it out, and think that they can just grow duckweed to feed their fish, and have a "zero input" system.. but they soon find that doesn't work..you need input!
    i've looked up lots of info on duckweed, and for me it has it's place..
    i have three 55 gallon glass tanks, one 45, two 20's and 3 tens..
    in all my glass tanks,(besides sponge filters) i use duckweed to consume ammonia produced by crayfish (i've got a couple other plants in the tanks as well, not only to consume ammonia and nitrites, but as habitat for scuds crayfish and minnows), which are also an excellent supplementary fry/minnow feed by the way), and as it grows i thin out each tank every couple weeks, but basically every weekend i put several net "scoops" into the fish tank... the tilapia clean it up over night..
    but my primary feed is a mix of several varieties of commercial fish food (low to high protein)..
    if i was using raft tanks, i'd be concerned about mosquitos, and would populate the troughs with minnows to eat the larvae..the problem there is that the minnows will also eat the gammarus/scuds..
    in the end, it's all about balance

  3. #3
    Moderator urbanfarmer's Avatar
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    Re: The benefits of Duckweed/ or lack of benefits???.

    Quote Originally Posted by 15mules
    [commercial feed is] basically the same as our 10 pounds of duckweed
    False.

    Quote Originally Posted by 15mules
    If some of my findings is wrong, please explain it to me and help me see the benefit of duckweed. thanks for listening
    As you stated in a previous post (I think it was you) a few pennies difference in fish feed cost can make or break a commercial operation. Supplementing "free" duckweed for some portion of your commercial pellet feed will reduce the cost of a business owner. You are clearly focusing on the cost of the thing. There are benefits that cannot be monetized. For instance, you can buy some GMO, pesiticide laden corn for $1, let's say. You can buy the same corn, with the same protein, sugar content, etc, for $3 except this corn is not GMO, was grown without synthetic pesticides or fertilizers, and may generally be more nutritious because of trace minerals, higher content of vitamins, or whatever. Just because the protein matches up, hell even if it's the same species, it doesn't mean it's the same quality feed/food. The $1 corn is still cheaper though, sure...

  4. #4
    Moderator urbanfarmer's Avatar
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    Re: The benefits of Duckweed/ or lack of benefits???.

    Quote Originally Posted by keith_r
    but they soon find that doesn't work..you need input!
    I would argue that no natural system, anywhere on this Earth, requires human input to grow. I would further extend this premise to include properly designed AP systems as not needing human input (aside, perhaps, at initial construction). I have done it, the science backs it up, and it's actually a hell of a lot easier for a backyard gardener. Just food for thought...

  5. #5
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    Re: The benefits of Duckweed/ or lack of benefits???.

    Quote Originally Posted by urbanfarmer
    I would argue that no natural system, anywhere on this Earth, requires human input to grow. I would further extend this premise to include properly designed AP systems as not needing human input (aside, perhaps, at initial construction). I have done it, the science backs it up, and it's actually a hell of a lot easier for a backyard gardener. Just food for thought...
    I can comprehend the natural system does not need human input. I get that. The Earth was that way for millions of years. With an AP system that produces food, there is a loss of substance during harvest. How is the loss balanced without human input? The way I am imagining it, plant products and even fish are consumed out of the system. In a natural system, the creatures doing the consuming are part of the system. With AP, we are not a direct part of the system. Our waste products do not stay in the system. Please explain this to me, as I am very interested in efficiency and having a system that mirrors the natural way.
    Less irritating avatar since 02/27/14.

  6. #6
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    Re: The benefits of Duckweed/ or lack of benefits???.

    Quote Originally Posted by urbanfarmer
    Quote Originally Posted by keith_r
    but they soon find that doesn't work..you need input!
    I would argue that no natural system, anywhere on this Earth, requires human input to grow. I would further extend this premise to include properly designed AP systems as not needing human input (aside, perhaps, at initial construction). I have done it, the science backs it up, and it's actually a hell of a lot easier for a backyard gardener. Just food for thought...
    an ap system is far from natural....
    i'd like to see a zero input system that you can harvest fish and veggies from and is zero maintenance? (labor is input as well, unless you work for free and don't need any calories)

    i see ponds that people think are "zero input" ecosytems,, but to balance a pond the pond owner needs to input lots of energy and effort.. i really can't see an ap system working without lots of input in at least man power and some input in feed/nutrients

  7. #7
    Members 15mules's Avatar
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    Re: The benefits of Duckweed/ or lack of benefits???.

    Ok, so who is feeding their fish only duckweed, how much are you raising and feeding, how much input cost do you have in producing your duckweed, what kind of growth are you seeing in your fish?

    UF, I guess the point you are trying to make when you say "False" is that duckweed is natural or organic and fish feed is full of GMO corn and chemicals?? This would go back to my original argument for DW if a person is doing it because they want a self sustaining or totally organic system. I can understand that, but it does not make it economically better.
    As far as an AP system being natural, it is not, it is a man made ecosystem, just like a zoo or a man made pond, without human input it would die in short order.
    Comparing Aquaculture to AP to me is apples and oranges, Aquaculture is competing with cheap imorted fish and expects no secondary source of income such as produce, only fish. I would never build a AP system if I thought my primary income source would be the fish. This has been proven to not work. Several commercial AP systems I know of all say the same thing, they lose money on the fish sales. This is why they have moved away from high density stocking rates and went to low density stocking rates and focused more on plant production while maintaining minimum fish populations for proper water nutrients.
    But that is really for a different thread and a different topic. I just want to see some solid information on how duckweed can be economically produced and beneficial when the time, and input cost are factored in, because I just do not see it.
    Never show your ignorance, by thinking you know it all

  8. #8
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    Re: The benefits of Duckweed/ or lack of benefits???.

    I don't think you'll find anyone growing tilapia on just duckweed (at least not for long)....

    can i ask what "commercial" aquaponics systems you've seen mention that fish loose money?
    any successful business will take some marketing..

    if you grow show quality koi, you can sell a single fish for hundreds, if not thousands of dollars..
    or if you raise trophy quality fish, you can sell to taxidermists for big bucks.. i know a taxidermist that sells the trout he raises for over $100 each - he's also set up aquaponic systems in high schools, the kids grow the fish out (bluegill and yellow perch), and at the end of the year, the fish go into his trophy ponds..

    raise a few sturgeon and wait 10 to 15 years to harvest the caviar and make a small bundle...

    around here tilapia is cheap (around $5lb).. a backyarder couldn't compete.. but yellow perch sells for $15-$16lb..
    striped bass even more..

    with a 12 tank setup, you could harvest once a month for specialty sales (restaurants, farmer markets etc)

    so these "commercial" ap systems that are loosing money on the fish.. do you think they know the only way to make it work? or just figured out a "niche"?

  9. #9
    Members 15mules's Avatar
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    Re: The benefits of Duckweed/ or lack of benefits???.

    I will send you a pm about the fish thing, so maybe we can get some more info. on duckweed here.
    Never show your ignorance, by thinking you know it all

  10. #10
    Moderator urbanfarmer's Avatar
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    Re: The benefits of Duckweed/ or lack of benefits???.

    Quote Originally Posted by keith_r
    an ap system is far from natural....
    Whose fault is that?

    [quote=keith_r]
    Quote Originally Posted by urbanfarmer
    Quote Originally Posted by "keith_r":2giosuii
    but they soon find that doesn't work..you need input!
    I would argue that no natural system, anywhere on this Earth, requires human input to grow. I would further extend this premise to include properly designed AP systems as not needing human input (aside, perhaps, at initial construction). I have done it, the science backs it up, and it's actually a hell of a lot easier for a backyard gardener. Just food for thought...
    an ap system is far from natural....
    i'd like to see a zero input system that you can harvest fish and veggies from and is zero maintenance? (labor is input as well, unless you work for free and don't need any calories)

    i see ponds that people think are "zero input" ecosytems,, but to balance a pond the pond owner needs to input lots of energy and effort.. i really can't see an ap system working without lots of input in at least man power and some input in feed/nutrients[/quote:2giosuii]
    I'm guessing you put "zero input" in quotes because it's some kind of gimmick out there? I have no idea what that is, but I don't see why you can't grow some tilapia in a pond without having a human throw food or fertilizer in there, happens all the time...

    To clarify, no nutrient/food input to the system, but yes how could there be no labor? However, very little labor can be required. It depends how much you want to manage and play with the system. There will always be some labor required... who else is going to chew the food for you??

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