Interesting comparative situation on our two ponds this year. Upper pond received initial fert treatment on schedule. Lower pond did not. And it got too clear, and had a terrible outbreak of FA. Finally got the fert program going in May, got a good plankton bloom, and the FA died back over a period of a few weeks. The FA is not completely gone, but it's probably 80% gone. The bloom blocked the light and apparently killed the FA. The upper pond, which was fertilized early, has maintained a good bloom and had no FA issues. Based on this experience I certainly agree with the view that controlling sunlight penetration is an effective way to control FA. That's my nickel cause I'm outta pennies.
