What type of whole house water filtration systems are out there?

We moved to a house which is on well water. There is a whole house filtration system but it is not doing a good job of removing iron from the water. I see brown stains in commodes and they come back again one month after removing the stains. The system we have now is regeneration type which does not need any salt to be added. I want to know if there is a body of knowledge for layman home owner giving me a lay of the land about cost affective options available for filtering the whole house water efficiently.