Glad to hear the alum treatment worked!
Electrically charged clay particles can stay suspended a VERY long time.
If the alum works well, and you can have an enjoyable pond managed with the periodic introduction of some invasive species, then that should be just fine.
If not, then a 1-foot tall berm shouldn't be a deal breaker on the view from the house. The farther you move the berm from the edge of the pond, the better the visual appeal. Of course, the berm has to have 100% water exclusion to be effective. If there is a fixed low spot that you cannot alter, then that solution is worse than useless.
