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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.
Instructions: Thoroughly rinse the BioDenitrator with freshwater. Fill 50% (~5”) the reaction chamber with SupraPure sulphur media (99.9% pure). Next, fill the reaction chamber with 2-3” of coral-skeleton media. Make sure to leave a minimum of 3” between the top of the media and the top of the reaction chamber so that the inlet tube does not become clogged during operation and that you are able to see any air bubbles forming or trapped at the top of the BioDenitrator. For freshwater tanks with lower pH (pH 7.0 or lower), the coral-skeleton media is not required.
Once the media has been placed inside the reactor chamber, close off the lid and tighten all screws. Secure the Eheim pump to the top of the BioDenitrator with the Nylon screw and nut provided. Attach the “Einlauf” (inlet) and “Ausgang” (outlet) assemblies to the top of lid and to the Eheim pump. Using the tubing provided, connect both the “Einlauf” (inlet) and the “Ausgang” (outlet) to the tank. Make sure that the tubing is fitted tightly to prevent leaks! With both the “Einlauf” and “Ausgang” lines submersed under water, open the "Entlüftung" and begin to manually siphon water up through the "Entlüftung" tube to fill the chamber. The BioDenitrator must be installed lower than the tank’s, or sump’s, water level (for installations where the BioDenitrator is higher than the water level in the tank or the sump, a separate feeding pump is required).
Once the reaction chamber is completely filled with water, close the "Entlüftung" valve. Elevate the “Ausgang” line so that it is about 1” above the water line: this will allow you to monitor the drip rate more easily. Open the “Ausgang” valve fully and start the Eheim pump. Let the BioDenitrator run for 2-3 hours then throttle back the “Ausgang” valve to about 2 drops per second (effluent drip rate). Allow the BioDenitrator to run at this rate for one week: the effluent drip rate can fall to about 1 drop per second without causing any adverse effects.
After one week, reduce the effluent drip rate to 1 drop per every 2 seconds. Now, measure the NO2 (nitrite) level with a test kit. If the NO2 (nitrite) level is 0 ppm, change the effluent drip rate to 1 drop per second. Allow the BioDenitrator to run for 24 hours then test the NO2 level and NO3 (nitrate) level: both in the aquarium and of the effluent. If the NO2 level remains at “0” and the nitrate level of the effluent is lower than the nitrate level of your aquarium water, the BioDenitrator has begun reducing nitrate (NO3).
* If the nitrite (NO2) level is higher than 0 ppm, there is no need to test the nitrate (NO3) level as the result would in incorrect.
It will take 4-6 weeks for denitrifying bacteria to fully colonize the media in the BioDenitrator. After this time, you can begin to tune BioDenitrator by adjusting the effluent drip rate to obtain the maximum nitrate reduction rate. If the nitrate level is near zero, increase the effluent drip rate. If the nitrate level is high, reduce the effluent drip rate.
Please note that these units are built to order so there will be a slight delay in delivery