I think you're missing the overall reason behind my suggestion of testing the water. OP said they have an algae bloom and they don't know why. Performing a water test would give them some indication of the conditions currently present. OP didn't give a lot of details, but it does sound like this is a Summertime occurrence, so it could probably be narrowed down to either overfeeding or a build-up from Fall leaves still in the pond. Either of these situations could be determined by a simple water test, but the solutions are vastly different. As you already mentioned, algaecides are not a permanent solution in any situation, but this is a recurring problem. How can we give suitable suggestions to the problem without first knowing what conditions have caused this problem?