I have never treated a pond with Azolla but I did see a pond with it last year so I did a little research. I'm sure there are other options out there but I just thought I'd share what was told to me..."Galleon should provide excellent control within about 30-45 days at 20-30 ppb. You can also use 3 oz Reward and � oz SilEnergy/gallon of water and spray for quicker knockdown" I would contact the chemical manufacturers to verify these concentrations will work for your situation before you start. Good luck