Seachem de*nitrate

de*nitrate is a porous biological medium aimed at the last step of the nitrogen cycle: reducing nitrate, rather than simply processing ammonia and nitrite.

Key features

• Porous natural medium supporting nitrifying bacteria near the surface and denitrifying bacteria deeper in
• Aimed at nitrate, the parameter that otherwise only comes down through water changes
• Doubles as ordinary biological media when run at higher flow
• Inert and long-lived rather than a consumable

The anaerobic pockets that consume nitrate only form when water moves through the medium slowly. Oxygen has to be used up at the surface before the core can go low-oxygen. Run it fast and it behaves as a straightforward aerobic biomedia; run it slowly, ideally in a dedicated low-flow chamber, and the nitrate-reducing side has a chance to develop. That flow rate is the whole trick, and it is the part most people miss.

Nitrate reduction of this kind is slow and partial, so treat it as a supplement to water changes rather than a substitute. For conventional biological media, see external filter media. Local pickup at our Lethbridge store.