There are different types of filter media that fulfill different functions.
If you have had problems with manganese or iron in your water, you can, for example, clean your water with a special filter that has a filter pulp adding oxygen. Oxygen makes the iron in the water precipitates out when it comes in contact with air. When the iron has been precipitated it later picked up by the water filter.
The water filter having a so-called automatic back flushing, thus the filter cleans itself periodically, adding often associated with flushing fresh oxygen in the resin while washing away of iron stuck in the filter.
If you have problems with your water become acidic and have far too low a pH can buy a filter that has a lot of filters that help to raise the pH of your water.
If you have more of these problems, you can combine different types of filter masses to get the best results.
For water that contains too much calcium is another type of technology that will help you with water, namely ion exchange technology. This technique involves adding the salt tablets in the filter that activates the resin. The filter will then have the ability to catch up calcium and magnesium and descaling thus the water.
You need to periodically replenish, replace or clean the filter mass. How often you need to put the new filter material depends partly on the type of mass you have, what type of filter mass sit in and how your water is. The more particulate filter media captures the more often it needs to be replaced.