NatuReef Controlled Biological Denitrification Reactors

  • Now you can drop your nitrate level down to undetectable levels (0ppm) and keep them there!
  • Eliminate water changes. Most people do not have the time nor expertise to mix water and change large quantities religiously. If you do perform monthly water changes to reduce nitrates, you can never totally eliminate nitrates from your tank. The results are a see-saw effect on the nitrate level which is not found in natural systems. If you have a large bio-load, these water changes are even more important and difficult to perform.
  • SAVE MONEY! Water changes cost money. Salt is not cheap. The water in most cities is barely fit for human consumption, let alone delicate corals and fish. Some city water supplies even contain nitrate to begin with.
  • NatuReef Denitrifiers convert Nitrate to Nitrogen gas, which bubbles out of the reaction chamber. The nitrates are not converted into another hard-to-extract form.

The NatuReef cyclic denitrifing process has other important benefits:

  • Increases Alkalinity
  • No tricky electrochemical methods (which produce other dangerous chemicals such as Nitrogentetraoxides)
  • Consumes free organic material
  • Recycles inorganic chemicals so they become usable again (e.g. Iodate is reduced to Iodide)
  • Zero Phosphates can also be achieved! (with the Phosphagone option)

Principle of Operation

The Natureef cyclic denitrification reactor utilizes a specialized strain of faculative marine micro organism “Micro Cult” to catalyze the reduction of unwanted nitrate ions to harmless nitrogen gas. To perform this chemical tranformation the micro organisms need a readily available source of energy, and “Nitagone” to fill that requirement. The reaction chamber operates in a cyclic mode, whereby the water within the chamber becomes anoxic (nearly devoid of oxygen) for a predetermined time. During that interval the “Micro Cult” with in the chamber performs the chemical transformation. At the end of that peroid the chamber is allowed to become oxic again (mixed with oxygen containing water) and the cycle is repeated. Hence the term “cyclic denitrification”.

The Natureef Controlled Biological Denitrification Reactors all are controlled by the CDEX controller. The controller pumps water from the aquarium sump into the reation chamber to mix with the “Micro Cult” already in the reactor. After the chamber is filled with the aquarium water, the contoller doses a measured amount of “Nitrgone” into the reaction chamber. A brief period of time goes by for the “Nitrgone”  to be mixed with the water in the chamber. This process allows most of the dissolved oxygen to be depleted. Then following this process most of the nitrate ions have been converted to nitrogen gas. The gas then exits the reaction chamber as nitrogen bubbles. Finally the controller ingages the pump in the aquarium sump to pump new water into the reation chamber. The processed water drains (flushed) back into the sump area of the aquarium as the new water is being pumped in. The chamber allows the water to mix with the new water and is again returned to an oxic condition. This completes one cycle of cyclic biological denitrification.


Controlled Cyclic Biological Denitrification for the marine aquarium was designed and developed by Coral Reef Research, Inc. The process has been applied and proven since the mid-1970’s. The process involved is actually quite simple: using cultivated microorganisms that convert unwanted nitrate ions to nitrogen gas, which leaves the aquarium. We also control the microorganism growth rate. Hence the nitrogen conversion capacity is proportional to the amount of nutrient supplied. The nutrient Nitragone, consists of organic carbon and growth enhancers. This solution composition is critical to proper operation of the reactors. Complete nitrate reduction can be obtained without the formulation of unwanted byproducts that occur during the oxidation/reduction process of denitrifcation. The number of times per day that the chamber completes the process, multiplied with the chamber volume, determines the rate at which nitrates will be removed from the system.

The complete denitrifcation system consists of a controller/feeder, a reaction chamber, and a water diverter (except the CDE series). All model reaction chambers require a small powerhead for circulation. We recommend a HAGAN 201 or any small powerhead for that purpose (purchased separately).

The controller / feeder is a digital timing system that allows for incremental dispensing of the Nitragone fluid via a peristaltic pump and precise micro-bore tubing. It also provides the signal that activates the diverter and allows tank water to enter the reaction chamber for a predetermined length of time.

Many people have terrible algae growth coupled with slow coral and anemone growth. They have done everything by the book and still have a nitrate problem. The denitrifier is the answer to the problem. Sure, there are other methods available to reducing nitrates, but none of these give you the advantage of fully stocking your tank with fish and invertebrates and not dealing with a high nitrate situation in the long term. In addition to these benefits, this process is a simple and a natural method of removing nitrate from the water.