10 Inch Carbon Block Filter, 5 Micron
Stage three. The last thing the membrane sees.
Extruded coconut-shell carbon block rated 5 micron, 10 by 2.5 inch. Chlorine, pesticides and the organic compounds behind taste, plus a second sediment pass. It is also the membrane's bodyguard: free chlorine destroys a thin-film membrane, and this is the stage that removes the last of it.
What it does
Carbon block is powdered carbon pressed into a solid tube, so the water is forced through millions of tiny channels instead of around granules. That gives it two jobs: a finer chemical pass than the GAC stage, and a 5 micron mechanical filter that catches the carbon fines and anything the sediment stage missed.
When to change it
Every 6 months, with the sediment and GAC stages, as the pre-filter kit. A carbon block that has stopped working gives no sign until the membrane starts letting salts through, by which time the membrane is the part you are replacing.
Fitting
Housing three. Gasket end up. Flush for five minutes on the first fill.
