Proper sizing of your softener makes your softener run more efficiently and the softener lifetime will be extended. Efficiencies of your softener can save you money and therefore pay for the cost of your softener.
If you size a softener too small it will regenerate too often. By regenerating too often you will use a lot of salt and water. Both of which will increase your operating costs. It will be forced to work harder and the lifetime will be decreased.
If you size a softener too big it won't regenerate often enough. Hardness sticks to the resin too long and is harder to remove. This in turn is hard on the resin and decreases the lifespan. Bigger units are designed for more water usage. By using more water they work more efficiently. When only small amounts of water are being used on a regular basis, bigger softeners will use more salt and water to regenerate. Therefore not saving you the cost difference in efficiencies.
A sizing formula can be found on our FAQs page. Doing it properly will protect your water softener investment.