I have noticed lately that my shower seems to be building up a lot with a lot of gunk. I am not sure why lately this is happening as compared to a year a go. I have heard that there are shower filters that can help with this problem. I have never heard of, or been able to change a shower filter before. I am not even sure where to buy them, or how expensive they are. Can I install them myself, or is it something I would have to have someone come to my house to install for me?