The mixed bed resin filter is filled with a special ion exchange resin and removes salts dissolved in the water. It is only suitable for water treatment and cannot be used in the aquarium. The mixed bed resin filter has nothing to do with a softening system.
The salts dissolved in the water consist of positive and negative particles that cause the electrical conductivity. The charged particles are exchanged for H+ and OH- at the ion exchanger. The two H+ and OH- particles combine to form water. As a result, the dissolved salts are bound to the ion exchanger and thus removed from the water and the electrical conductivity of the water is significantly reduced. Since the capacity of a resin is limited, towards the end of the capacity not all electrically charged particles are captured and the conductivity of the effluent water is slowly increased. At about 2-3 µS/cm conductivity, the resin should be replaced.
A resin filter cannot retain particles or uncharged contaminants.
It is possible to treat tap water only through a mixed bed filter. However, it makes more sense to place this filter downstream of a reverse osmosis system, as this already removes about 95% of the salts and significantly reduces the capacity of the mixed-bed resin. The resin filter can thus treat approx. 20 times more water than without a reverse osmosis system connected in front of it.
Only in combination with a reverse osmosis system can the resin filter reject particles and uncharged pollutants.