I read here that algaecides are better to use as a preventative measure than a treatment. I never had an algae problem with my pool – only in my 2nd year. I added one dose of poly-quat algaecide two weeks ago. My question is how often do you need to add algaecide using it as a preventative measure? Does it dissipate over time? Since there isn’t any test I know to measure levels I thought someone here might have some insight. Thanks