Basics of Filtration
Fundamental to the success of a healthy aquarium is theThe most familiar chemical adsorbent is activated carbon.

stable aquarium environment made possible by scheduled

Activated carbon should be a little larger than pin-head inwater changes and filtration. Water changes provide

size. When washed and dry, it should be dull and not shiny.

systematic removal of wastes not normally removed by

When placed in water, it should hiss. It should also tend tofiltration and restoration of a balanced ionic environment.

float at first. Be careful of charcoal, however, because it is dull

No system exists, despite irresponsible or misinformed

and floats, but does not hiss. Charcoal is usually very soft,

claims to the contrary, that can replace water changes.

crumbling easily between the fingers and is usually available
only in pea-size. Good activated carbon is hard but fragile,

There are five primary types of filter configurations:feels hard and does not crumble, but fractures under finger

undergravel, wet-dry, hang-on-the-back, canister, and box.

pressure. Not all true activated carbons are equivalent. TheThe undergravel filter has limitations, but remains a reliable

most commonly available carbons are economical waterand simple design. The box filter is inefficient, since water

purification grades, usually derived from wood or nut shells.

can easily by-pass the filter media. The hang-on-the-backCoconut carbons are best suited for gas filtration, not water

filter is an excellent mechanical filter, but the canister filter isfiltration. These are not bad carbons, but you may wish to

the most efficient chemical filter, and, overall, is probably theseek out some better grades. The best carbons are usually

best design. The wet-dry filter is basically a gas

produced from bituminous coal and have highexchange filter that provides direct loss

porosity and low density. They shouldof ammonia to the air as well as

also have low ash content to minimize

excellent conditions for biologicalimpact on pH. Seachem’s

filtration.

MatrixCarbon™ is unique in that it
incorporates each of these features in a

There are three types of filtration: mechanical,biological, and chemical. Mechanical filtration is merely
the removal of insoluble particulates from the water by some
type of sieving device, such as floss or foam. Biologicalfiltration is the removal of ammonia and nitrite waste fromwater by Nitrosomonas and Nitrobacter bacteria,
respectively, and is the most essential of all filtration types.
The most reliable aerobic biological filter is the wet-dry.
Anaerobic biological filtration converts nitrate to nitrogen.
Seachem’s de*nitrate™ is an innovative media for biologicalfiltration that permits both aerobic nitrification andbiological removal of nitrates. Equipment has also been
designed for algae scrubbing where nitrate and organic waste
is removed by algae culture. Chemical filtration is the direct
removal of solutes by adsorbtion. The most importantfunction of chemical filtration is the removal of nitrogenousorganic waste. This is vital, because such waste is both
inhibitory to the biological filter and increases the load on thebiological filter.

spherical pellet that possesses ideal hydrodynamicproperties. Cylindrically shaped pellets are designed for airfiltration. All activated carbons release phosphate, despite
claims to the contrary, and only those that release the least
should be selected for reef aquaria. Seachem’s Renew™ is anexcellent, economical substitute for activated carbon,
particularly in freshwater. It has an equivalent capacity fororganic removal as many carbons; it does not release
phosphates, does not alter pH, and it darkens on exhaustion.
Another chemical adsorbent option is Seachem's SeaGel™.
This material is formulated from MatrixCarbon™ andPhosGuard™ (Seachem’s phosphate and silicate removingmedia) and is optimized specifically for aquaria whereorganic color body and acid removal is required without theintroduction of phosphate. It is particularly effective incorrecting algae problems in both marine and freshwateraquaria. It is not recommended for phosphate bufferedfreshwater aquaria. It produces ultrapure and ultraclearwater.

1000 Seachem Drive • Madison, GA 30650 • 706.343.6060 • FAX 706.343.6070 • 888-SEACHEM • www.seachem.com

Other types of chemical filtration include synthetic
adsorbents, ion exchangers, and zeolite. Zeolites are white,
dusty clays, usually sold for removing ammonia fromfreshwater. Zeolites are ineffective in seawater or evenfreshwater that contain modest amounts of salt. Zeolites are
ineffective for removing nitrates. Synthetic ion exchangers
are useful in freshwater to control ionic balance, remove
ammonia, nitrite, and nitrate. In marine water, ion
exchangers can remove some nitrite and nitrate, but have nosignificant effect on ammonia. They can also help to retard
ionic imbalance. But, generally, the most useful function ofion exchangers, in both fresh and marine water, is organic
removal, and in this they excel. Although not an ion exchange
process, this ability of ion exchangers to remove organics isphenomenal and works in both marine and freshwater alike.
Seachem's HyperSorb™ is a premium synthetic adsorbent
with outstanding organic removal capacity and ionicmanagement abilities. It is ideal for all types of water,including marine, brackish, and a broad spectrum offreshwater from acid to alkaline. It has all the advantages ofcarbon and none of the disadvantages. HyperSorb™ changes
color progressively as it becomes exhausted, and then can beeasily regenerated with ordinary household chemicals.
Regeneration is near 100% effective and can be performed
repeatedly. Purigen™ is a premium grade synthetic
adsorbent that retains all of HyperSorb's™ qualities alongwith the added advantage of possessing a four fold greater
capacity (than HyperSorb™) with virtually no impact on
trace elements.
CupriSorb™ is a narrow spectrum, synthetic adsorbent
based filter material for removing copper and heavy metals
from either freshwater or marine water. It extracts all types ofcopper, including chelated copper, and remains effective
until it turns a deep blue-black color. It may be regenerated
repeatedly. If placed in continuous service, it will gradually
extract even precipitated copper and make invertebrate
culture possible in tanks previously heavily treated withcopper. CupriSorb™ is a powerful copper specific chelating
resin. Competing products are not chelating products, but
merely cation exchange resins. Such resins can remove
copper from freshwater but are ineffective in seawater.