And I'll add that the best way to treat staining is to remove the cause
of the stains, not to treat the symptoms; the resulting stains.
Regular softeners can remove up to 1-2 ppm (mg/l) of ferrous, clear
water, iron. And if you buy right, others will remove up to 5 ppm of
Although a softener should not be used as a filter, although resin is a
fairly good filter, only a few brands of softeners, actually the
control valves used, require a prefilter. Most prefilters will cause
more problems than they cure. They ca nactually cause the softener to
be unable to remove all the iron in the water. If the water is clear
when drawn, no softener requires a prefilter; IOWs it's more marketing
than factual if someone suggests a prefilter simply because you are
buying a softener.
Any softener that is allowing rust stains on fixtures needs a resin
cleaner periodically and/or it is not sized correctly and/or is missing
certain internal features to assure removal of the iron found in the
Quality Water Associates