What Is Purigen?

Purigen is a completely synthetic adsorbent and organic scavenging resin that is extremely useful in saltwater aquarium filtration.


Purigen – Ultimate Filtration

It is made up of tiny spheres of macro-porous polymer beads that bind nitrogenous compounds to the microscopic pores on its surface. The nitrogenous compounds it binds would otherwise breakdown to produce ammonia, nitrite and nitrate.

This stuff seems to last a very long time — 6 months and more — before losing its adsorbent capabilities. You’ll know when it is exhausted when it turns dark brown or black.

Purigen And Trace Elements

Unlike activated carbon, Purigen has minimal impact on important trace elements in the saltwater aquarium.  Its use can therefore be recommended in aquariums with sensitive corals.

Purigen Placement

New Purigen can be used right out of the bottle without rinsing.

It should be placed in an area of medium flow, preferably in a sump or in a hang-on filter compartment.

It should be noted that it’s particles are extremely tiny so using a regular nylon mesh bag normally used for carbon and other media will just not do — the beads easily escape through the tiny holes of mesh bags, creating a huge mess in your tank. Don’t make the same mistake as I did by using a regular mesh bag!

For this purpose, Seachem manufactures a specialized nylon mesh bag for Purigen — aptly called ‘The Bag’.  ‘The Bag’ is made of very fine 180 micron nylon mesh and is resistant to bleach and acids.  It is also great for regenerating Purigen in, as we will discuss later.

And for even greater convenience, Seachem also manufactures a pre-bagged 100ml version of Purigen. Pop one or two bags into the sump and it’s good to go.

Because of its fine particle size, Purigen cannot be used in a fluidised reactor.

Re-Generating Purigen

Purigen can be regenerated although I prefer to buy a fresh batch every 7 to 9 months or so.

Seachem states that it can be regenerated by soaking it for 24 hours in a 1-to-1 ratio of household bleach and water. Seachem’s ‘The Bag’ is impervious to bleach so you can go ahead and soak it in the bleach solution with the Purigen in it.

Be sure to use unscented bleach and a non-metallic container or bowl to soak the Purigen in. After 24 hours, remove the bleach and water solution, and rinse the Purigen well in freshwater. Soak for a further 8 hours in freshwater and 2 tbsp of dechlorinator per cup of water until there is no smell of chlorine. Do not use if chlorine is still present after the entire process. Use a chlorine test kit if in doubt!

Purigen Maintenance

Since Purigen lasts such a long time, it is good practice to rinse it out every couple of weeks to remove detritus that might clog up the media.  I prefer to use aquarium water from a water change or de-ionized water.  Purigen will readily adsorb impurities in tap water.

Purigen And Activated Carbon/Chemi-Pure

Since Purigen does not deplete trace elements it is ideal when used together with smaller amounts of activated carbon or Chemipure.

Purigen is a potent ally in helping to keep the water in our saltwater aquarium clean.

Links to more Saltwater Aquarium Filtration pages:

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