Common Filter-Maker Jargon
Used in Descriptions
Absolute: means
absolute. An absolute 5-micron filter is one proven to remove
all particles of five-microns or larger.
Carbon: Sometimes
called charcoal, filter carbon is a manufactured product that is
made by heating a substance like coal, nut shells, or bone to
very high temperatures in the absence of oxygen. The resulting
product is shot full of nooks and crannies that have a
magnet-like attraction for chemicals. Filter carbon works by the process of
adsorption--catching and holding contaminants on its surface. It
is the preferred treatment for almost all chemical water
contaminants and is a great enhancer of taste and odor. For
chlorine removal, nothing equals it, although KDF, discussed
below, works well in some cases.
Carbon Block: Filters
in which the carbon is pressed or molded into a tight block-like
structure. Generally speaking, carbon block filters are more
effective than GAC filters.
Ceramic:
is used to make very tight filters whose absolute filtration
rating is too tight to allow the passage of bacteria and
pathogens like cryptosporidium or giardia. Ceramic cartridges
"purify" water by straining out pathogens, but they
have no effect on chemicals or heavy metals.
CTO: Stands
for "chlorine/taste/odor" reduction. Filter makers use
this to designate filters for which the maker only claims
aesthetic improvement. Often filters in this category do
more than promised, but the filter maker isn't making claims
other than aesthetic enhancement.
GAC:
Granular activated carbon. The term refers to specially
processed or "activated" filter carbon, or more
loosely to loose-fill filters in which the
carbon is of essentially the consistency of coffee grounds.
Gravity Filter. A
filter that works without water pressure. You pour water into an
upper chamber and it slowly filters through to a lower containment
vessel.
Ion Exchange:
Process used in water conditioning in which one constituent of
water is
exchanged for another by passing water through a specially
prepared resin. A water softener, for example, exchanges calcium
ions for sodium ions to get rid of "hardness"
(calcium). In countertop filters, ion exchange resins are
sometimes added to get rid of problem contaminants like
lead. Ion exchange cartridges also exist which remove
nitrates and sodium.
KDF: is a
metallic (copper/zinc) filter medium used to remove free
chlorine, lead, iron, and hydrogen sulfide. It is usually mixed
with granular activated carbon. KDF cartridges are expensive,
but they usually last a long time. Another advantage is that KDF
is mildly "bacteriostatic," meaning that it inhibits
the growth of bacteria within the cartridge.
Micron: A standard
size measurement used by filter makers. A micron is equal to one
millionth of a meter, or about 0.00003937 inches. This is an
area where smaller is usually better, but only to a point. A
5-micron filter is generally assumed to be more effective than a
10-micron, but a filter isn't effective if water won't go
through it. For drinking water filters, somewhere around
0.5 microns, or 1/2 micron, is about the lower practical limit.
That's tight enough to remove bacteria, but big enough to allow
water to pass through. For whole house systems that require
higher flow, 0.5 microns is usually too tight.
Nominal: means
"more or less." A nominal 5-micron filter is one that
removes a high percentage of 5-micron particles.
Radial Flow Cartridge:
A cartridge in which the water flows from outside to inside and
uses the entire surface area of the carbon. Our MatriKX
cartridges are open-ended radial flow systems. Our Di-Tech
cartridges are "axial" flow, meaning that water to be
filtered enters one end of the cartridge and flows out the
other.
Siphon Filter.
Water is "sucked" from a container, through a filter,
to a vessel located beneath it. Siphons can provide much better
flow rates than standard gravity filters. They can be used when
no water pressure is available, in camping or emgergency
situations, for example. Countertop filters can be easily
modified to act as siphon filters during emergencies.
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