Duckweed chokes out everything including underwater plants that create oxygen. All the oxygen the duckweed gives off during photosynthesis just goes right up into the air.
I had duckweed. I aerated, I added pond dye, I added muck-eating enzymes to cut down on the nutrients the duckweed was feeding on. VERY LIMITED success.
I ended up killing the duckweed by adding whitecap/sonar in the early spring before it started to bloom. Very good success--hardly any duckweed anywhere. My 2nd year I hit it again with another application--this time the watermeal is zapped too.
Controlling algae without duckweed starts with pond dye. Keep the sunlight out by filtering out the wavelengths of light algae use to photosynthesize.
Other than that, if you hit it with sonar once and then let it die and get out of your way, a big fountain or bubbling aerator might agitate the water enough to keep it from growing back but it will still grow at the edges.
I hate to use chemicals too but duckweed produces so much volume of weed that it's really annoying. i could scoop out wheelbarrows of it EVERY DAY and not keep up. The stuff multiplies amazingly fast.
I have an update question--yes, I successfully zapped my duckweed and watermeal, but I'm getting algae around the outskirts. In my opinion, it's a lot easier to mechanically remove and compost since it's pretty manageable.
My question is to you experienced pond owners--is algae floating on the surface cumulative year over year? Will the surface algae expand without treament or removal? I can stand a little around the perimeter but don't want it taking over.
Thanks!
