Duckweed question?

[lmm600]

I have recently come into taking care of a simple two pond system. It relies on evaporation for its discharge. My problem is both ponds are @80% covered with duck weed. I know I can mechanically rake it or use a herbicide. But does anyone know more options? Any possible drawbacks to any of the above? Thanks

 

[bimr]

The herbicide is not really a good idea. Killing the duckweed will leave organic matter in the water causing water quality issues. You need to mechanically harvest the duckweed.

With no discharge from the ponds, one would expect that the salt concentration would eventually surpass the duckweed tolerance for salts.

 

[civilperson]

Duckweed should not lessen the amount of water leaving by evaporation/transpiration. Plant cattails and wild rice for a blend of plant species. The stems will support biological eaters of suspended solids.

 

[roncity]

Maybe divide the ponds to allow one side to be taken out of service and the water level lowered to kill the weed .
See

http://www.ci.austin.tx.us/news/2007/drawdown_extended.htm