Pond Boss Forums AERATION Should I aerate? River fed pond

Did you get the water test results back yet?

The aeration system should not be the cause of the problem. The only time I have seen an aeration system kill fish in a pond is when the owner didn't start up the system correctly and mixed too much of the anoxic bottom water with the upper water column, killing the fish.

Duckweed is an indicator of high nutrient levels and very little wind on the surface of the pond. Usually water that stays in a pond builds up nutrients. Draining and re-filling the pond should flush out the nutrients. I agree with Bill Cody 1,000% that you should get the river water tested for nutrient levels. Toxic Blue Green (B/G) algae needs specific parameters to grow. There are many, MANY different species of B/G algae but VERY FEW are toxic. Just because someone says you have B/G algae doesn't mean that it's toxic.