This is so embarrassing to admit, but I can't grow duckweed. I'm actually a really good gardener and I can't grow one of the planets most noxious weeds. I have tried it in a stock tank and in a small plastic container, I have tried using organic liquid fish fertilizer and then Pete's professional powdered fertilizer. I even tried keeping it on top of a 5 gallon betta tank and it died - I think there was too much water movement. The duckweed never completely goes away in my non-fish tanks but never grows enough to feed the chickens. What am I doing wrong? How is it possible not to be able to grow duckweed?