I have a MacClean softener and filter. I just changed the media in the filter and decided I should change the media in the softener as well. It's 25+ years old and never changed. It's a CS1500 and I can find no where on the Net regarding the type of media to use. Actually nothing about MacClean at all, even Cuno has no info. I know it takes 1.5 Cubic feet. Does anyone know what type?