All about Denitrator

Originally Posted by atom

Schuan Nitrate Filter is small as compare to NR5000 which is quite huge. It should be compare to NR1000.

IMO, sulphur based is more suitable for marine reefer than freshwater hobbyist. . The reaction series (4 NO3 + 3 S = 2 N2 + 3 SO4 or 2 H2O + 5 S + 6 NO3- à 3 N2 + 5 SO4-- + 4 H+) involved is acidic (sulpuric acid)and thus it must be tied up with very good buffering. As such most reefer will combine the sulphur based denitrator with a calcium reactor.

Using sulphur based denitrator will result in excess sulfate which is not common for freshwater but not so in seawater.

Sulphur-based denitrification in freshwater is based upon autotrophic denitrification by sulphur-oxidizing bacteria, such as Thiobacillus denitrificans and Thiomicrospira denitrificans.

The smallest Schuran Nitrate Filter 100 supports up to 3000 liters of water which is similar to the NR5000. The only difference is that the Schuran Nitrate Filter can be sulphur based or alcohol-fed depending whether using it in a seawater or freshwater environment. The NR5000 is media dependent.

I deployed the Schuran with Siporax filling and fed it with vodka via a time-based pump giving near zero NO3 during my Tropheus & Kigoma & MBlue Frontosa fishkeeping days and since then never look back. But now onwards to using sulphur beads for my marine reef tank.

Fyi, it was a pain in the neck using the NR1000 despite using the SP3000 dosing pump together with the ORP controller.

Originally Posted by Sunburst

The smallest Schuran Nitrate Filter 100 supports up to 3000 liters of water which is similar to the NR5000. The only difference is that the Schuran Nitrate Filter can be sulphur based or alcohol-fed depending whether using it in a seawater or freshwater environment. The NR5000 is media dependent.

I deployed the Schuran with Siporax filling and fed it with vodka via a time-based pump giving near zero NO3 during my Tropheus & Kigoma & MBlue Frontosa fishkeeping days and since then never look back. But now onwards to using sulphur beads for my marine reef tank.

Fyi, it was a pain in the neck using the NR1000 despite using the SP3000 dosing pump together with the ORP controller.

All manufacturers specify their denitrator as "how much it can support"? I never really like this statement because it is too "grey". Take an example of NR1000 using sp3000 dosing pump. The dosing pump flowrate is quoted at 3 l/hr and means that 72 l/day. If I have a 500 litre tank and a bioload of 10 mg/l of nitrate per week, the NR1000 takes about 6.9 days for a complete turnover. Basing on this info, the NR1000 will definitely be fighting a losing battle against the bioload and furthermore, this is based on Ideal Condition. NR1000 is quoted to handle up to 1000 litres of water! I treat most the specifications with a pinch of salt. Sorry.

Another common "grey" specification is bio-media. It is always specified as "the amount of water (volume) it can handle. Currently there are no industrial standard governing all these claims.

I had the opportunity to have a dissussion on denitrifcation with Dr Manfred from Aquamedic during the Aquarama. This is my conclusion for carbon based denitrator.

increase performance -- increase feeding --increase anaerobe pollution.

There is a problem with the above equation. When I said increase performance, it is meant the output is increase at 0 nitrate level. The problem is the size of the denitrator!

Originally Posted by atom

All manufacturers specify their denitrator as "how much it can support"? I never really like this statement because it is too "grey". Take an example of NR1000 using sp3000 dosing pump. The dosing pump flowrate is quoted at 3 l/hr and means that 72 l/day. If I have a 500 litre tank and a bioload of 10 mg/l of nitrate per week, the NR1000 takes about 6.9 days for a complete turnover. Basing on this info, the NR1000 will definitely be fighting a losing battle against the bioload and furthermore, this is based on Ideal Condition. NR1000 is quoted to handle up to 1000 litres of water! I treat most the specifications with a pinch of salt. Sorry.

Another common "grey" specification is bio-media. It is always specified as "the amount of water (volume) it can handle. Currently there are no industrial standard governing all these claims.

Personally the SP3000 dosing pump doesn't play other than pushing water to the NR1000 as I am using an ORP Controller which switches the SP3000 dosing pump on/off when it registers between -250mV and -280mv. This is to ensure consistent level of NO3.

However if you don't use the ORP controller then the SP3000 plays an important part together with a switch valve to ensure the right amount of water is drip into the unit.

Having said that the water flow must go through the denitrator depends on the nitrate level of the water to be treated: the more nitrates, the lower the flow must be, otherwise you will find part of the nitrates at the output.

Then the next most important step is to adjust in the following manner:
- If the flow rate is too low, you will get a rotten egg smell at the column's exit due to a production of sulfurous hydrogen (H2S). This will rarely happen for really low flow rates.
- If the flow rate is too high, you will detect nitrites or nitrates in the output water.
- If the flow rate is correct, you should obtain 0 nitrates.

With that the turnaround of having zero nitrates for your tank is determined by the rate at which the water from the tank is "converted" by the denitrator which could takes up to 6 to 8 weeks and even longer depending on the tank's nitrate level.

Likewise similar problem exists for the NR5000 together with the SP3000 dosing pump or any other denitrators unless used in conjunction with a ORP controller ....

Take note that there are less than a handful of such controllers in the market today for aquarium application that can control redox up to -500mV.

Bro Atom ... you're absolutely correct by commenting that sulphur based denitrator is meant for marine environment and not suitable for any freshwater tanks.

Bro Sunburst ... you're also correct that using Siporax media for your Schuran denitrator in a fresh water environment because I am using this media as the biological media for my filtration system instead of biohome.

Very educational contributions from both of you.

Originally Posted by Sunburst

Personally the SP3000 dosing pump doesn't play other than pushing water to the NR1000 as I am using an ORP Controller which switches the SP3000 dosing pump on/off when it registers between -250mV and -280mv. This is to ensure consistent level of NO3.

However if you don't use the ORP controller then the SP3000 plays an important part together with a switch valve to ensure the right amount of water is drip into the unit.

Having said that the water flow must go through the denitrator depends on the nitrate level of the water to be treated: the more nitrates, the lower the flow must be, otherwise you will find part of the nitrates at the output.

Then the next most important step is to adjust in the following manner:
- If the flow rate is too low, you will get a rotten egg smell at the column's exit due to a production of sulfurous hydrogen (H2S). This will rarely happen for really low flow rates.
- If the flow rate is too high, you will detect nitrites or nitrates in the output water.
- If the flow rate is correct, you should obtain 0 nitrates.

With that the turnaround of having zero nitrates for your tank is determined by the rate at which the water from the tank is "converted" by the denitrator which could takes up to 6 to 8 weeks and even longer depending on the tank's nitrate level.

Likewise similar problem exists for the NR5000 together with the SP3000 dosing pump or any other denitrators unless used in conjunction with a ORP controller ....

Take note that there are less than a handful of such controllers in the market today for aquarium application that can control redox up to -500mV.

I agree totally with regards to ORP controller.

My equipment list for my current denitrification.

- NR1000 x 2
- AquaMedic mV computer using AquaMedic ORP probe x 2
- SP3000 x 3 (decom - too slow)
- IKS aquastar vario x 2
- Deltec solenoid valve x 2
- 1 x Biostar-flotor
- 1 x Sander C100
- 1 x FR (prefer my DIY than Skimm FR) with AquaMedic 4mm carbolit

My standby (currently in storeroom) set for the new tank.

- NR5000
- AquaMedic AT-controller
- Gorman Rupp Mini pocket bellow pump

Originally Posted by WaterZoo

Bro Atom ... you're absolutely correct by commenting that sulphur based denitrator is meant for marine environment and not suitable for any freshwater tanks.

Bro Sunburst ... you're also correct that using Siporax media for your Schuran denitrator in a fresh water environment because I am using this media as the biological media for my filtration system instead of biohome.

Very educational contributions from both of you.

I was actually considering using cerapores but after looking at the anaerobe slime, decided against it.

I didn't want to distract your trend of thought, but looks like the coast is clear now. Anyway, just one query about ORP, could you go through it for the benefit of those who are not familiar? Thanks.

Originally Posted by Spakase

I didn't want to distract your trend of thought, but looks like the coast is clear now. Anyway, just one query about ORP, could you go through it for the benefit of those who are not familiar? Thanks.

I will make an attempt. There are 2 outstanding areas which I think they very important to take note of before anyone plunging into the denitrator.

1. ORP - what does it do and how to benefit from using it

2. The denitrified output. Is that all to it?

ORP - What does it do and how does one benefit from it.

Denitrification is as natural as nitrification. It depends on the level of (in our case) dissolved oxygen present within the water column itself. For the case of a denitrator, very low level or no dissolved oxygen must be achieve for it to work.

What is ORP? It stands for Oxidation Reduction Potential and the measuring unit is denoted as mV. Sometimes it is also known as pollution index. In our case, it is the measure of the relative oxidizing power of the water. Sounds simple? It is, perhaps, the single most complicated chemical feature that aquarists will typically encounter! I will try to explain as simply as possible and how it can be applied on the denitrator.

In our aquarium, just imagine it is a battlefield comprises of oxidizers and reducers. ORP is the measurement of who is winning and who is losing. We cannot have only either one of them as the livestock will be very very dead.

The majority of oxidisers are O2 and the minorities are O3 (ozone), H2O2 (hydrogen peroxide), 3O2 (triplet oxygen) and other variety of oxygen radicals with also include chlorine and chloramine. The oxidisers need to get electrons and they get them from the reducers.

The reducers are: inorganic compounds such as ammonia, iodide and sulfide. Vitamins C is a very powerful reducing agent.
The reducers come from fish food, metabolic waste products, the breakdown of dead organisms, and certain additives put into the aquarium. The reducers all want to get rid of electrons, and they virtually throw them at the oxidizers.

To be continue.....