Korallin BioDenitrator Nitrate Filter S-1502 w/o Pump

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$363.49 $499.95
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*Eheim 1048 pump required and sold separately


  • Large internal volume with a small footprint
  • Optimal efficiency through high internal recirculation and fast Nitrate removal
  • Top-loading lid with detachable tubes for easy maintenance
  • No feeding liquid required!
  • Ultra-pure Sulfur (Sulphur) filling 99.9%
This revolutionary design makes denitrifaction easy and efficient. Feeding to the bacteria is not necessary; just put the unit into your system and let it run for a few weeks, denitrafication power will be activated once the unit is broken in.

The design is based around the C-1502 reactor and combine Sulfur (Sulphur) media with calcareous media to offer a high level of Nitrate removal. The recirculation method is far more efficient than simple single pass filters. As it includes reactor media, the pH is fully buffered and enriched with calcium before being returned to the tank.

With the build quality of the S-1501 reactor and recirculation, these offer very efficient nitrate removal. After a running in time of approximately 3-4 weeks (for the bacteria to colonize the chamber) this unit will, for example, reduce 100 liters with 50mg NO3 to 0 in 3-4 days.

Because this denitrator makes use of the design of Calcium Reactor C1502, once the nitrate problem has been solved, you can easily turn this denitrator into a Calcium Reactor with some additional parts (sold separately).

Comes with 1.6kg high grade pure Sulfur (Sulphur) and crush-coral substrate.

Korallin S-1502 - Rated for up to 250 gal. Reactor height: approx. 15.75"; Diameter: 4.50"; Footprint diameter: 6.30"; Included filter media: 6lbs 

More Info:

The Use of Sulfur (Sulphur) Denitrators
Over the last few years, Sulfur (Sulphur) denitrators have grown in popularity in Europe from humble beginnings in public aquaria to being used in cutting edge integrated filter systems.

Existing Methods
Before we recommend a new process to customers, we make sure we have tested them ourselves on our own systems. We have long held the view that if you design a natural system with the management of nutrients in mind, nitrate and phosphate can be almost forgotten. But with all the best laid plans, you often end up with excess nutrients. These may be due to a higher load of fish or inefficiency in the system’s denitrification abilities. Either way; even the best systems can end up with a nagging 10-20ppm of residue nitrate. The options currently available to resolve excess nitrate would normally take the route of increasing water changes, adding more live rock, or increasing things like the deep sand beds or adding mangroves.

An option that many people have tried is the slow flow denitrator. These rely on anaerobic bacteria, colonising a suitable medium and the flow of water being slow enough, to become depleted of oxygen to create an environment they can thrive in. These bacteria will then multiply and consume the nitrate in the low oxygen water. If well set-up this method can be quite successful.

Enter Sulfur (Sulphur) Denitrators
Guy Martin from Ecole Nationale Supérieure de Rennes did the original work on fresh water treatments plants, although the science may pre-date this. The work was transferred to the marine environment and used by Michel Hignette, curator of the MAAO aquarium. A pilot project was launched. Since then the experiment was done on a much bigger scale, at the MAAO, as well as in the Grand Aquarium in Saint-Malo. All of these systems have been a great success and the systems have proved a real boon in large scale aquariums where the management of nitrate is often an after thought, when feeding displays stocked with large fish with voracious appetites. After these successes, there have been many Sulfur (Sulphur) denitrators added to private aquariums across the continent.
  • Simple to set-up and manage.
  • Needs no additional feeding with carbon based foods.
  • Works well without the cost of additional electronic control.
  • Will supply additional calcium to the tank when used as per instructions.
  • Units can be ran in series for management of higher nitrate levels.
  • Long lasting: up to 2-3 years.
  • Units can be easily refilled.

Product Manuals & Documentation

Korallin BioDenitrator Nitrate Filter S-1502 w/o Pump

Owner's Manual available for download in Adobe PDF file format

Manufacturer Info

Korallin is a German based company who is a manufacturer of specialized aquatic components and accessories for the advanced marine aquarist.



Experience Level: Expert

Now you can sleep at night!

I've been using this denitrator for 4 years now on 200 to 30 gallon reef tanks, and my nitrate levels have remained at zero! Along with regualar cleaning and water changes this has been one of the best purchases i have ever made, other than my controller.

2 out of 2 found this review helpful

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Experience Level: Intermediate


this is a very good denitrator... it start to work fast... in just 2 week the nitrates when down to 10% then to zero nitrates there's only few things left in the instruction paper..need more detailing ,or photos

7 out of 10 found this review helpful

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Experience Level: Intermediate

Million dollar piece

instructions were lacking but the results are speechless! before setup,nitrates were on a constant 80+ppm even after water changes on a 125gal fish and reef tank.after 1 week the output was reading 0ppm and in 2weeks,aquarium nitrates dropped at 40,within 4weeks at 10.i also added more corals and fish.this product is a must and i suggest gettin one.maintain waterchanges and proper water chemistry for a healthy saltwater tank.

4 out of 4 found this review helpful

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Sir reef alot from LAUREL, MD UNITED STATES


Experience Level: Intermediate

Best investment

I have a 265 gallon reeftank which is loaded with coral and large fish. I battled high nitrates for years until I purchased this product. My nitrates were typically between 30 and 40ppm. Three weeks after installing this product, my nitrates have plummeted and have remained at zero. My corals have never looked so good and my calcium levels are fine. Buy one of these before you buy a calcium reactor which it can be converted to. This was the single best investment for my reeftank.

7 out of 7 found this review helpful

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John N. from

Korallin BioDenitrator

I have a 72 gallon tank heavily loaded with corals and fish. I could not get the nitrates under 40-50 other than massive water changes. I installed this unit and after 5 weeks nitrate are 10.

6 out of 6 found this review helpful

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