I've been in the water treatment industry for over 23 years and can't believe some of the size units that are being recommended to residental home. A 2.5 or 3 CF is just over kill unless your hardness is 80 to 100 GPG or you have 10-12 people living in the home. Some say size it based on the flow rate with all the faucets on in the home. Now how many times will you have every single water using devise on at the same time in your lifetime? That means your dish washer, clothes washer, every sink hot and cold, ice maker, every shower hot and cold and all outside hose bibbs on if they pass through the softener. Now I can understand if you have multiple body sprayers or a 5000 SF home needing a bigger than normal softener, but a 2.5 or 3 Cf unit on a 2000 SF home with 20 GPG hardness and 3 people is just plain overkill IMO.