PLucas wrote:
>
> Mark Thorson > wrote in :
>
> > I'm watching Ask This Old House, and they're replacing
> > a water softener. Actually, they're using the old tank
> > but replacing the head and the resin beads. As they were
> > dumping out the old beads, there was all this black muck
> > at the bottom of the tank. They didn't comment on that.
> > I'd hate to think of my drinking water passing through
> > that crap.
>
> The "black muck" was most likely carbon, which is used in most filters.

But carbon is usually a replacable cartridge, not a layer
under the resin beads, because the carbon gets used up.
The resin beads are recharged with a brine and reuseable
for many cycles.