Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants another watermeal question

I treated my pond early in the season when my watermeal and duckweed first started to multiply. I used one quart of sonar to treat. My pond is 1.09 acres, 9' average, 12'max. The treatment worked great for about 2 months then I started noticing more and more duckweed and watermeal starting to appear again. After looking closely at it I notice it still has the white dieing look but it is still showing up. I am using a pool net to skim it off but it seams to be getting worse as we are in a slight drought here. Normally by this time of the year my pond was 100% covered and thick. I have a lot of leaves and cottonwood cotton falling into the pond right now and my pond has turned to the tea color I have read about. I use aeration with one diffusser and will be installing a larger 4.5 cfm with 2 diffusers here soon. Is there anything I can do to help stop this or do I need to add more sonar? I am new at this and my wife says I am going to have to slow down on the spending. Any advice would be greatly appreciated.

Aaron, when using Sonar at a quart per acre you will kill every plant in the water including the duck weed. This can cause the water to stain. When going after duck weed I would wait until until the pond is completely covered. You can sometimes only kill whats there and when the product is completely gone or the ppb levels are too low to kill duckweed you will see regrowth. Sonar or Avast can only kill what is there and is not a preventative.