iSpring FM25B Iron Manganese Reducing Big Blue High Capacity Replacement Water Filter, 4.5" x 20" Efficiently reduces iron (3.0 -&gt; 0.01 ppm), manganese (1.0 -&gt; 0.01 ppm) Stable and satisfactory performance at wider ph range 5.8 - 8.6 and temperature range 40 - 113F Higher linear velocities than conventional media delivers high flow rates & very low pressure drop Lasts up to 3 times longer than greensand because the catalytic media is not consumed in the process Safe for Drinking water applications, tested by independent third-party to meet NSF/ANSI standard