As we all know, hard water is the enemy of good coffee - it will make coffee taste heavy, powdered, boring, and damage your equipment.
Resin water filter are the most common way to reduce the hardness of water - they are relatively cheap and the most basic version can even be "regenerated" and reused.
The "hardness" of water is an index to measure the concentration of calcium and magnesium minerals in water. This is divided into "temporary hardness" and "permanent hardness", the former refers to the concentration of calcium bicarbonate and magnesium bicarbonate, and the latter refers to all other calcium and magnesium minerals, such as sulfate and chloride. The sum of the two, or the total concentration of calcium and magnesium, is called "total hardness".
These minerals have different effects on coffee flavor and equipment, so the purpose of resin water filter is to selectively remove mineral ions in water, such as calcium (Ca2 +), magnesium (Mg2 +) or bicarbonate (h2c032 -).
There are two types of ion exchange resin water filter media that can be used in water purifiers. One type of positive exchange is called cation resin water filter media. Another type of negative exchange is called anion resin water filter media. The two resins do the same job, they only remove different minerals. Cation resin water filter media removes calcium, magnesium, iron and hydrogen. The anion resin water filter media removes chlorine and sulfur.
Ion exchange medium is an integral part of water treatment system because it is the only water softener. For this reason, small resin beads are used to attract ions that cause hardness and to replace them with harmless sodium ions. Without it, you'll filter out water that still contains dissolved minerals.