Korallin BioDenitrator Nitrate Filter S-1502 w/ Eheim 1048 Pump

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  • 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 calciumcarbonat.

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; Eheim 1048 Pump.


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; Eheim 1048 Pump. Comes with 1.6kg high grade pure Sulfur (Sulphur) and crush-coral substrate.

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/ Eheim 1048 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.


1 year manufacturer warranty

49 Reviews



Experience Level: Intermediate


The instruction neglect to describe the overall set-up and the schematic of the plumbing is poor. Here is my take: The pump is used to make a high flow loop into and out of the reactor from which (and to which) a slow drip of water from your tank/sump flows. This keeps the reactor anaerobic with sufficient turbulence to keep the bacteria happy. So the large diameter short tubing sections connect to the pump to make a loop into and out of the reactor and the small lines go to the tank (sump). I used wire ties to prop the pump up in position. I hope this helps with set-up.

3 out of 3 found this review helpful

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Experience Level: Expert


So my nitrates have been doubling every day in my 365 gallon discus/south american tank so I had to do 200 gallon water changes everyday. I installed this denigrator last Thursday and the effluent is already coming out with 0 nitrates and my nitrates have stabilized around 10ppm and seam to be going slightly down already! Though the manual is not perfect it's easy to assemble and get running. I'm very please and my fish seem to be too.

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Experience Level: Intermediate

Best tank purchase EVER!!!

First, the bad: as others have mentioned, the manual is mostly worthless. Neither of the pictured hoses was included, meaning one of the valves was missing as well. Between youtube and a quick trip to the hardware store, however, those two negatives were eliminated quickly. Those two issues were annoying enough that I normally would not give a 5 star rating, so the fact that I AM giving a 5 star rating speaks to how much I love this product and how well it works. Cycling can take a few weeks so patience is required, but once it is cycled you will be dancing a happy dance because your nitrate export problem has just been solved without the need for a deep sand bed or biopellets or any of that other stuff. My tank is so simple and yet so beautiful. I don't even need a sump with this thing. A modified canister filter (all mechanical filtration removed), a protein skimmer, a bunch of live rock and this denitrator are absolutely the only filtration I'm using and my fish and corals are doing great! Oh and did I mention that my nitrates are ZERO despite not having done a water change in 6 months? Well not zero anymore, my tank got TOO clean and so I run this a little less efficiently than I could to keep the corals happy. Since my water changes have become all but non-existent, I do dose trace elements weekly. With this up & running, I NEVER have to dose calcium but my alk depletion rate is a little higher than before. Dosing addresses this just fine, but I'm really after as little maintenance as possible. Therefore I am most likely going to be adding a calcium reactor in the near future. Once that is done, apart from daily feeding and weekly dosing of trace elements, I will have a maintenance-free tank. I have not done a water change in the 6 months since this unit cycled and everything is doing great.

6 out of 7 found this review helpful

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Experience Level: Intermediate

Expensive but really works

Included instructions are accurate but minimal, difficult to follow and no pictures. However youtube is easy to follow. I had been struggling with Nitrates for years with my 55g. Up and down, up and down. Installed the Denitrator on 1/6/15 with tank at 40 ppm Nitrates. After it cycled (which took about one week) steady slow Nitrate decline. On 2/10/15 Nitrates are at 5 ppm and continue to decline. Marked improvement in corals. And as the product advertises, the media helps buffer the pH although I still need to dose more Alk than I was before installing the denitrator. Overall I am extremely satisfied - solved the most stubborn problem for me with nitrate control. 5 stars for sure. Expensive but absolutely works perfectly and with almost zero maintenance.

2 out of 2 found this review helpful

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Experience Level: Intermediate

Korallin Biodenitrator

I have had a saltwater tank for approximately 20 years. What would turn me off of the hobby were algae problems. It didn't seem to matter how many water changes and cutting down on feedings I did the algae problem was there. My tanks have been mostly 90 percent SPS and loosing a colony hurt. I picked up a Korallin Biodenitrator and ran it for 3 weeks before I noticed that my nitrate level was "0". I've never seen my tank look this good and I recommend this product. This is simply the best product that I have ever purchased for my tank.

2 out of 2 found this review helpful

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Experience Level: Expert

Works with patience

I could write pages about this.. It's a complicated product for most. However it does work, it is effective. I have a few you tube videos on it. Part1 &2. They help out if needed.

2 out of 2 found this review helpful

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Experience Level: Intermediate

Money wasted

Ineffective. I made a DIY denitrator roughly 1.5 years ago. The PVC sulfut denitrator-the plans are in several places online- it was very effective but very sensitiv and the pumps pumping the watr to it were "cheap" and needed a lot of adjusting consistently-this was the reason for purchasing the Korallin. THe Korallin has had no effect and it's been up and running for roughly 8 weeks. Spend your money on better pumps and use the DIY denitrator-it actually works.

0 out of 5 found this review helpful

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Experience Level: Beginner


Wow it's can lower nitrate in 6 days to zero

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Experience Level: Intermediate

THE BEST Piece Of equipment

I have Red Sea Max 65 pretty heavy stocked I have carbon reactor ,gfo reactor, bio pellets reactor , I changed stock skimmer for expensive Deltec Internal Protein Skimmer MC500 for $500, I change water regularly Still my nitrates around 20 ppm some time little bit higher So I decided to spend some more, and buy this Korallin reactor I can tell you it works it almost hard to believe but it all shows light yellow consistently. The only advice is to follow instructions and in about a week or so I assure you you will see the results. I would say it is the best $400 I spent on the system.

2 out of 2 found this review helpful

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Experience Level: Beginner

So far, not so good

So for a while I was getting 0 nitrates coming out of it, but in my 500 gallon setup the 4002 is just having no effect. Even though it is rated for a 700 gallon setup. I think I will had a second 4002 and see if that makes a dent.

0 out of 2 found this review helpful

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