Seachem Purigen 100mL Bag
Purigen is an effective, safe and reusable alternative to activated carbon.
From the manufacturer:
Purigen® is a premium synthetic adsorbent that is unlike any other filtration product. It is not a mixture of ion exchangers or adsorbents, but a unique macro-porous synthetic polymer that removes soluble and insoluble impurities from water at a rate and capacity that exceeds all other competing products by over 500%. Purigen® controls ammonia, nitrites and nitrates by removing nitrogenous organic waste that would otherwise release these harmful compounds. Purigen’s impact on trace elements is minimal. It significantly raises redox. It polishes water to unparalleled clarity. Purigen® darkens progressively as it exhausts, and is easily renewed by treating with bleach. Purigen® is designed for both marine and freshwater use.