[waterfilters]

Here is a cartridge that will work nicely for you: DGD-5005-20 Water Filters and Pentek DGD500520 Sediment Filter for 20 inch Big Blue Whole House Housings Although, if you have less than 3ppm Iron, you may want to consider a system like this: Iron Reduction Whole House Water Filter Cartridge System by Pentek

Thank you,
WaterFilters.NET