I'm posting this for a friend. He has a 2 year old self contained pond approx. 1 surface acre that is 3 feet deep in the shallow end falling 1 foot every 3 feet to a depth of 10 feet. His water is still murky and has never cleared completely. He has been told to add Alum but doesn't know how much to add without over doing it. Can anyone help? Thanks in advance for any responses.