SweetLighter

I'm no expert, just a believer in "general wisdom," so I'm having a hard time understanding this..

Activated carbon is supposed to do its thing because each little piece of carbon has millions of microscopic holes in it. So these millions of holes work like a sponge and absorb stuff from the water, like DOC, but also trace elements and minerals, so it's not a good choice for a planted tank..

Purigen also is said to work like carbon, each little synthetic bead has millions of microscopic holes.

So if it works the same way as carbon (like a sponge with micro holes), how does it only absorb "bad" stuff but leave the "good" stuff (like trace elements, vitamins, etc) alone?

I believe the quote from Seachem is "Purigen's impact on trace elements is minimal."

niko

The pores in both materials provide bigger surface and nothing else.

The effectiveness of both does not depend on mechanical trapping of particles.

Physico-chemical forces (tiny electric charges) trap the particles. This can be roughly explained by using two magnets - the "+" charged side of one of the magnets attracts the "-" charged side of the other. But two "+" sides push each other away.
Iron for example is charged "+" (Fe2+ or even Fe3+) and if the Purigen beads are charged "+" iron will not be attracted.

The resin (Purigen) is engineered and made in such a way that the physico-chemical forces attract and "keep" only particles with certain electric charges. Resins can be "recharged" because of that - by mixing the resin with some chemical that pulls stronger the same particles that the resin absorbs.

--Nikolay

SweetLighter

Thanks much for the explanation.

I would be interested to know any further insights..

Seachem

I apologize for my delay in responding. Niko, spot on with your response and thanks.

SweetLighter

Thanks.

Any chance of finding out what chemicals Purigen does actually attract? Maybe a list of ions it affects / does not affect?

This would be very helpful for many customers I think who want to know what it is doing to their water chemistry (marine tanks, planted tanks, species tanks, etc.)

Seachem

Simply put, Purigen's structure is such that it's greatest affinity is for nitrogen containing organic material. It also has a very small affinity for inorganic nitrogen (like nitrate) but this is dwarfed by the former.