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