I recently set up a 150 gallon saltwater tank for the kids to put the creatures they catch out of the canal we live on. The water is stained brown and has not cleared up as much as I would like. I am running a wet dry system with bio balls and sand. after 4 days the water is better but it is still stainded and I need to know what to do to clean it up? Any ideas. I would not like to change out 150 gallons with fresh clear water from the beach, but if I can't solve this problem I will have to. Help!