Nitrite In 7 Year Old System

[Courtney Aldrich]

I am pretty sure all nitrate detection methods in the hobby reduce nitrate to nitrite and then use the Griess reaction to make the pink color.

I learned recently that zinc metal destroys nitrite and confirmed it in the lab. I wonder whether the amount of nitrite destroyed is constant across kits and whether the Hanna chemistry which uses different zinc reduction conditions affects nitrite differently. More lab lab work might sort this all out.

Yes, all nitrate test kits that generate a pink color use the Griess reaction that measures nitrite generated by reduction of nitrate. Consequently, all nitrate tests kits will have interference by nitrite unless they remove the nitrite. The degree of interference is largely impacted by the efficiency of the nitrate reduction, thus a method that has 1% efficiency will suffer from tremendous interference from nitrite (e.g. 1 ppm of nitrite will appear as 100 ppm of nitrate). There are many standard methods to remove nitrite interference by selectivity pre-reducing the nitrite before assaying for nitrate. This can be accomplished by treating the sample with sulfamic acid or ascorbic acid for a given time to remove interfering nitrite, then quenching the excess reductant (sulfamic acid or ascorbic acid) and assaying for nitrate. Presumably, the Tropic Marine Test kits employ this method.

 

[Dan_P]

Yes, all nitrate test kits that generate a pink color use the Griess reaction that measures nitrite generated by reduction of nitrate. Consequently, all nitrate tests kits will have interference by nitrite unless they remove the nitrite. The degree of interference is largely impacted by the efficiency of the nitrate reduction, thus a method that has 1% efficiency will suffer from tremendous interference from nitrite (e.g. 1 ppm of nitrite will appear as 100 ppm of nitrate). There are many standard methods to remove nitrite interference by selectivity pre-reducing the nitrite before assaying for nitrate. This can be accomplished by treating the sample with sulfamic acid or ascorbic acid for a given time to remove interfering nitrite, then quenching the excess reductant (sulfamic acid or ascorbic acid) and assaying for nitrate. Presumably, the Tropic Marine Test kits employ this method.

Great information! I am currently using 2% urea and concentrated HCl. Was not aware of these other methods. Thanks

 

[Lasse]

Presumably, the Tropic Marine Test kits employ this method.

Probably not. You first test for nitrite. You use an acid and the reagent for nitrite. After that you test for nitrate, Acid, metal powder and reagent for nitrite. You take your nitrite result - multiply this with 100 and subtract from the nitrate result. The Pro method. For the normal test - multiplier is 50

Sincerely Lasse

 

[Courtney Aldrich]

Great information! I am currently using 2% urea and concentrated HCl. Was not aware of these other methods. Thanks

I've attached some papers if you interested in learning more.

 

[Dan_P]

I've attached some papers if you interested in learning more.

This is a most generous gift. Thank you.

 

[Aqua Man]

Yes, I measured NO2. I assumed there shouldn’t be nitrite in an established aquarium. That belief is so strong I am still trying to figure how the measurement can be wrong. There is even nitrite in freshly prepared Instant Ocean!

Interesting. So, if no3 is on the high side and a person does a water change with water containing no2 the result is still no3 on the high side?

Mostly because of test kit interference?

Why would any salt mix contain no2?

 

[Randy Holmes-Farley]

Interesting. So, if no3 is on the high side and a person does a water change with water containing no2 the result is still no3 on the high side?

Mostly because of test kit interference?

Why would any salt mix contain no2?

Impurity in something else. Nothing in life is totally pure. :)

 

[Dan_P]

Interesting. So, if no3 is on the high side and a person does a water change with water containing no2 the result is still no3 on the high side?

Mostly because of test kit interference?

Why would any salt mix contain no2?

Great questions! I have found nothing so far to indicate that the nitrite reading is a fluke but I am still thinking of ways it might be.

 

[Dan_P]

Possibly the closing chapter of this thread. It seems by dosing chelated iron (wide orange line), Fe (II) gluconate (Seachem Flourish), I have driven down the nitrite in my system to an undetectable level. I will point out that I stopped dosing iron and the nitrite level stopped dropping, but then continued to drop when the iron dose was continued.

I also looked at what else was going on when I detected nitrite. I was just ending vinegar dosing. I wonder if this is evidence to support @Belgian Anthias conjecture that carbon dosing has a negative effect on the nitrification bacteria, in this case the nitrite oxidizing bacteria. Too bad I wasn’t monitoring nitrite over the previous several months of vinegar dosing.

 

[Lasse]

Its a well known fact that a high DOC level favour the growth of heterotrophic bacteria. These bacteria grow up to 30 - 50 times faster than the nitrification bacteria and could therefore take up available space - hence concur out the nitrite oxidizers from space to grow. All biological nitrification in waste water plants aim to first minimize the DOC concentrations before the nitrification step, A tip - in waste water nomenclature they talk about BODx (BOD5 or BOD7) instead for DOC - but it refer to the same thing - available organic carbon for heterotrophic bacteria growth.

Sincerely Lasse

 

[taricha]

It seems by dosing chelated iron (wide orange line), Fe (II) gluconate (Seachem Flourish), I have driven down the nitrite in my system to an undetectable level. I will point out that I stopped dosing iron and the nitrite level stopped dropping, but then continued to drop when the iron dose was continued.

Do you think that the Fe was more likely to encourage the NOB, or boost photosynthetic productivity?

 

[Dan_P]

Do you think that the Fe was more likely to encourage the NOB, or boost photosynthetic productivity?

When I tested my sand for nitrification in Instant Ocean I noticed no nitrite was produced. That got me thinking my system might be depleted in a micronutrient. Since I only have iron, I tried that. I was thinking NOB, but had no good reason for it. The Ulva became a monster plant in the bucket algae scrubber and might have benefitted, taking up NO2 because NO3 is under 0.1 ppm.

In retrospect, with my five day old biofilms consuming ammonia and not producing nitrate, I don’t know what to think about the N chemistry in my system.

 

[Dan_P]

Its a well known fact that a high DOC level favour the growth of heterotrophic bacteria. These bacteria grow up to 30 - 50 times faster than the nitrification bacteria and could therefore take up available space - hence concur out the nitrite oxidizers from space to grow. All biological nitrification in waste water plants aim to first minimize the DOC concentrations before the nitrification step, A tip - in waste water nomenclature they talk about BODx (BOD5 or BOD7) instead for DOC - but it refer to the same thing - available organic carbon for heterotrophic bacteria growth.

Sincerely Lasse

Great info Lasse, thanks. Dan

 

[Lasse]

The Ulva became a monster plant in the bucket algae scrubber and might have benefitted, taking up NO2 because NO3 is under 0.1 ppm.

My five cents. The Ulva was iron depleted. With plenty of iron it works like the song - first we take the ammonium, then we take the nitrate :D

SincerelyLasse

 

[Anxur]

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