An algal bloom is the start of the food chain! Many people on Pond Boss deliberately fertilize their ponds to create a bloom.

The fertility of your pond has almost certainly been slowly increasing for the past three years.

However, with the good comes the possibility of the very bad. As the experts above point out, a fish kill is now possible.

Do you live at your pond? I don't know how much time you have from the point you start to observe fish piping for oxygenated water at the surface to the point that you start to suffer a fish kill. (Maybe the experts can estimate that?)

Perhaps make a plan now, so you can execute the plan at a moments notice if needed?