I used SONAR concentrate, very simple and effective. Others here can tell you more about calculating concentration, and application process. You do need the proper dose to sit in the same volume of water for up to 30 days. So if you have inflow and outflow of water or water turnover it is harder to achieve that needed dose of Sonar for the whole time.

There is benefit from a fall application and then a repeat spring application, but a good spring application should still work well.

It is pricey!! PM me if you only need a small amount.