Anyone else out there for hard water solutions?
Just to clarify, hard water is hard because of calcium and magnesium. If you're trying to get rid of those you'll want a water softener, not a water filter.
In your first post you mentioned chlorine and fluoride, which are a separate set of two issues. Getting chlorine out of water just requires a big enough carbon filter. You'll need a completely separate alumina filter element to reduce (not remove) fluoride.
So the first step is probably to decide what you're trying to remove from your water. If you're having trouble with scale on your showerhead or a lack of suds from soap/shampoo, you're bothered by hard water and a filter won't help. If your shower water smells bad (like a public pool) you're bothered by chlorine and you want a charcoal filter. ....I honestly have no idea why you'd want to remove fluoride from your shower water, but if that's your priority I'm sure someone somewhere sells an alumina filter element for a shower head filter.