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  1. #11
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    Re: How to feed duckweed

    A question for the duckweed experts - I setup a dedicated duckweed tank with a small amount of duckweed that I had quarantined for some time. The plants seem to multiply and spread to the whole tank, which is integrated into the AP system, but they later contract, never getting to densely cover the tank. I have not been harvesting the plants, waiting until the tank is saturated, but this is going slowly, and a portion of the plants seem to be dying (turning grey).

    The tank has four 100W equivalent CFL's over it, temp is 80-90F in the room, water temp is ~85F, and humidity is ~70%. So what is keeping the duckweed from flourishing?

    Roger,

    Don't mean to hijack your thread, but figure that this is inline with the topic and the answers may be helpful to more than just myself.

  2. #12
    Members Roger L.'s Avatar
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    Re: How to feed duckweed

    No hijack taken Eddie. I am having problems and am looking for that one bit of info I have missed and then away I go. I hope! Everyone says how easy it is to grow so I got to thinking my thumb must be made of concrete.
    At what point did our government cease to be of the people, by the people, and for the people?

  3. #13
    Moderator urbanfarmer's Avatar
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    Re: How to feed duckweed

    Quote Originally Posted by eddiemigue
    A question for the duckweed experts - I setup a dedicated duckweed tank with a small amount of duckweed that I had quarantined for some time. The plants seem to multiply and spread to the whole tank, which is integrated into the AP system, but they later contract, never getting to densely cover the tank. I have not been harvesting the plants, waiting until the tank is saturated, but this is going slowly, and a portion of the plants seem to be dying (turning grey).

    The tank has four 100W equivalent CFL's over it, temp is 80-90F in the room, water temp is ~85F, and humidity is ~70%. So what is keeping the duckweed from flourishing?

    Roger,

    Don't mean to hijack your thread, but figure that this is inline with the topic and the answers may be helpful to more than just myself.
    Define slowly.

  4. #14
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    Re: How to feed duckweed

    i've found that once it spreads, you have to start harvesting, if it overcrowds itself it will start to die off..
    duckweed grows cyclically,, there's some pretty interesting reading on the net, but the gist of it is that duckweed doesn't flower, it reproduces asexually.. the "daughter" plants have shorter, and shorter roots as it reproduces, until the roots are too small, when many of the plants will "die off"..then the cycle starts with the remaining surviving plants that manage to grow some roots..
    i think it's a good idea to have a multiple cultures of duckweed...i have it in all my glass tanks, with different light durations, and will take a handful from one to the other tank to keep mixing up the "gene pool" of the duckweed, since i started doing this i haven't had a single "die off"

  5. #15
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    Re: How to feed duckweed

    My duckweed tank has been setup for about a month, and in this time vegetation looks sparse, and is not multiplying as I would have expected. I thought that this would double every few days, and it seems to be growing at a snail's pace.

  6. #16
    Members Roger L.'s Avatar
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    Re: How to feed duckweed

    Eddie, that is the same thing I have noticed. It does fine in the pond I got it from and I even brought some of the pond water back this time to experiment with in another vessel outside. I would check on it but there is thunder and lightning out right now, no time to be outside.
    At what point did our government cease to be of the people, by the people, and for the people?

  7. #17
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    Re: How to feed duckweed

    what are you "feeding" to your duckweed tank?

  8. #18
    Members Roger L.'s Avatar
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    Re: How to feed duckweed

    I cycle the water in the fish tank to the duckweed and have even put in some Maxicrop to help it along.
    At what point did our government cease to be of the people, by the people, and for the people?

  9. #19
    Moderator urbanfarmer's Avatar
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    Re: How to feed duckweed

    Quote Originally Posted by Roger L.
    I cycle the water in the fish tank to the duckweed and have even put in some Maxicrop to help it along.
    That's got a ton of salt in it. What's it say on the bottle? 1% Na??? And salt doesn't evaporate; it just builds up in the system!

    Salinity (Salt) Stress. Another stress factor is salinity, the concentration of sodium chloride in the water or soil. Worldwide, salinity is a major factor in what plants can grow where. Salinity can be high because of the presence of sea water, as in tidal marshes and estuaries, or because of leaching from saline soils at inland locations. Duckweeds, like many plants can tolerate a small amount of salt. Small amounts are even stimulatory for growth (figure). However, above a threshold (>60 mM NaCl), growth is begins to be inhibited. At yet higher concentrations, duckweeds cannot survive.


    Figure: Growth of Lemna minor in diluted sewage with added amounts of salt. Error bars are +/- standard error.
    Growth conditions starting with three replicates of 10 plants/each were: seven days at 20 C, 2700 lux from CW fluorescent lamps, in 100 mL 2% swine waste in 125 mL bottles with loose-fitting clear plastic lids. Regraphed from Stanley, RA and Madewell, CE (1976) "Chemical tolerance of Lemna minor L." Tenn. Valley Authority, Muscle Shoals, Al. Circular Z-72, 17 pp. (Polycopy).

    Just FYI, >60 mM NaCl is about >3 ppt NaCl.

  10. #20
    Moderator urbanfarmer's Avatar
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    Re: How to feed duckweed

    Quote Originally Posted by eddiemigue
    A question for the duckweed experts - I setup a dedicated duckweed tank with a small amount of duckweed that I had quarantined for some time. The plants seem to multiply and spread to the whole tank, which is integrated into the AP system, but they later contract, never getting to densely cover the tank. I have not been harvesting the plants, waiting until the tank is saturated, but this is going slowly, and a portion of the plants seem to be dying (turning grey).

    The tank has four 100W equivalent CFL's over it, temp is 80-90F in the room, water temp is ~85F, and humidity is ~70%. So what is keeping the duckweed from flourishing?

    Roger,

    Don't mean to hijack your thread, but figure that this is inline with the topic and the answers may be helpful to more than just myself.
    If I had to take a wild guess, I'd say it's not getting enough light. It could be something to do with the water quality as well. The grey is probably mold eating your duckweed. Take a good picture. Maybe someone can spot something.

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