Reduced salt dosage, 6 pounds per cubic foot of resin versus maximum salt dosage, 15 pounds per cubic foot of resin may be used to gain salt efficiency. Marlo softeners are set up to take advantage of this savings wherever it is possible to use it.
The reduced salt dosage, minimum salt setting, may not be used if iron is present in the water. With reduced salt the resin is not fully regenerated which means the resin bed retains some hardness and iron would also be retained. The iron will eventually oxidize within the resin bed and iron fouling will result in lost capacity.
Minimum salt setting can be used to obtain a more exact sizing of a unit based on 20,000 grains per cubic foot of resin versus 30,000 grains at maximum salting. This results in a smaller, less costly unit plus salt savings can be 30% or more.
Example: 3 persons, 15 grains hardness, no iron
3 x 60 x 15 – 3240 grains per day
15,000 grain unit at minimum salt = 10,500 gr. cap./ 3240 = 3.24 days
(25,000 grain unit at maximum salt = 25,000 gr. cap. / 3240 = 7.70 days)
(25,000 grain unit at minimum salt = 16,500 gr. cap. / 3240 = 5.09 days)
ML-15S is best sizing.