Yep, the citrus "filter" is really some kind of "conditioner" (Nuvah2o i think it is called). It uses a citric acid cartridge to somehow make calcium ions "clump" together in a way that makes it pass right through your pipes without forming scale, and supposedly even eliminates existing scale.
Sounds like BS to me, but I share the well with my folks and my dad's contractor buddies reported good results from this thing so I installed it this spring at pop's insistence. I've got that hard water and several hundred yards of water line so if this works it should hopefully cut down on my maintenance a little bit.
Two years ago one of my hot water heater elements burnt out- as I was replacing the lower element I poked a finger in...yep, completely full of leeched calcium carbonate chunks up to the element. Nasty, nasty stuff. If this citrus deal can prevent that then I will be quite happy...for now I drain and shop vac all my H20 heaters every spring and fall.