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Weekend Duckweed Hunting

March 19, 2012

 Took a break from being wowed by my new wood pizza oven to go duckweed hunting over the weekend.

My favorite duckweed hunting pond is thriving in our prematurely hot weather here in KY. A month ago, duckweed was just starting to surface. Now, Lemna minor is covering the edges of the pond and  tiny Wolffia is beginning to show up.

I’d hoped to get enough duckweed from my last sampling so I wouldn’t have to make a second trip. Then I went and purchased twenty goldfish as a side experiment and wasn’t thinking when I temporarily housed them in with my  duckweed samples. You guessed it. The goldfish ate most of the duckweed within one day. Then it got so cold out that my poor little goldfish all died and there I was without goldfish OR duckweed. Sigh… Back to the drawing board…

This time, I’m housing duckweed in three new containers and experimenting with a $17 wading pool from Wal-Mart. It’s supposed to hold 500 gallons of water. My kids tested it out yesterday in hopes that I’d give it to them instead. As it turns out, they can have it. The thing is so floppy, I’d have to support it on all sides before I’d dare fill it with more than twenty gallons of water. I don’t know what I thought I’d get for $17…

 The best container for the money so far is a simple rigid kiddie wading pool for about $10. I try to avoid the ones with the little built-in slide. The round ones last several seasons if you drain and store them during the winter. Plus, they stack easily and are UV protected. I just wish they made them in a dignified green or brown. The duckies and colorful, fun waves on the sides do not lend to a serious endeavor.

Have got a couple of experiments going on. One is using urine as a nitrogen source for duckweed. Another is with a direct feed of grey water into a duckweed holding tank. Will keep you posted on the results.


4 Comments leave one →
  1. Steve permalink
    August 11, 2012 4:26 am

    Thanks for sharing the info! Did you try urine as a nitrogen source?


    • August 11, 2012 9:36 am

      Yes. It was about the nastiest experiment I’ve ever done. When I can work up the courage to try it again, it’ll be minute dilutions in a biologically active water system with plenty of ventilation, outdoors… away from my living quarters…down wind….

      My results from fresh urine in up to 1:100 parts fresh water killed off duckweed quite spectacularly. I did see a slow down in the kill rate at 1:100 vs 1:80. It took a good month for my largest test fail- about three inches of water in an old aquarium at 1:100 ratio to go from clear to duckweed death,cloudy and whew… to clear. I didn’t add more duckweed at that point but it would have been interesting to see if the water could support growth at that stage.

      The reports on successful use of diluted urine in vegetable gardens was alluring, but what soil has that my duckweed water did not have was a complete nitrogen cycle going for it. Also, my dilutions were probably still concentrated. Steve, you try it and let me know what works for you. Thanks for the question!


      • December 28, 2015 8:23 pm

        Tamra, if you did nothing to lower the pH of urine, then it is normal that ammonia would build up and kill duckweed.


  2. yassin permalink
    June 12, 2012 5:10 am

    Cool hunting site. I’ll be lucky to find one on my first “Treasure hunting” this weekend. VEry Excited ! 🙂


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