Iron in my water

I'm not sure this is the right place to post, but here it is...

We drilled a well last spring for our new house. The water was really muddy for about a month. The driller said to let the water run for about a week or two. We did (constantly for a month!). It cleared up throughout the summer, then when it started raining a lot, the water became a reddish color. We've been told the water has iron in it. There is a "whole house" filter on the well & we have to change the filter about once a month or more.

Does anyone know of a type of filter that takes the iron out of the water? Any other suggestions?

Thanks,
Cynthia