The biofilter's job is to detoxify waste products such as ammonia, nitrite and some phosphate. Controlling phosphates will naturally improve pond water clarity and overall pond conditions. Phosphate is a major nutrient that can stimulate undesirable pond conditions that result in unclear water.
Before considering buying any additional fish for your pond you should consider whether your pond is ready for its first fish (if a new pond) or is ready for some extra fish if an existing pond.
