Birm is a relatively inexpensive material which can be used for iron and manganese removal by oxidation. It requires a pH of 7 or more for Iron removal and pH 8 for manganese removal (it uses dissolved oxygen in the water to oxidise the metal). As it acts a catalyst it is not consumed so Birm doesn't require regenerating or topping up. Birm also has the advantage of acting as a filter, removing turbidity. If the pH of the water is too low pH correction may be required. Media life expectancy is 2 to 3 years.