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Lasse

Lasse

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I have used Hanna low nitrate checker some months and I´m rather pleased with it if you have readings below 5 ppm. However - when you need to dilute - you run into problems. You can´t dilute with RO water because the checker is adjusted to high chloride content and if you use newly mixed SW - you still get problem if it contain anything that will show up as nitrate in the test - and at least Red Sea pro (the red bucket) affect the readings. Even if you use pure NaCl in the water you use for dilution - it affect the readings, Let us say that the dilute water show up with 0.3 ppm NO3 - it will affect your final result with 3 ppm.

In order to avoid this problem - I do two tests. I use a volumetric flask of 100 ml and put in 3.5 g pure NaCl (table salt) - after that I fill the flask with RO water to the 100 ml mark. Mix well and suck out 10 ml of the mixed water with a syringer. After this I fill up the flask to the 100 ml mark again with 10 ml water from my aquarium. Mix well and put it away for a while.

From the syringer with 10 ml 35 promille water I take 7 ml and start the normal procedure for determine NO3 in a sample (the Hanna low nitrate procedure) The result I get from this pure water will be written down - last time it was 0.38 ppm.

Now I take the volumetric flask with my 10 times diluted sample - take 7 ml and start a new standard analyze of the nitrate in the diluted sample. Last time it show 3.5 ppm NO3.

Now the math starts - I diluted my tank sample 10 times with a saltwater that scontain 0.38 ppm NO3. It was 9 parts containing 0.38 ppm and 1 part containing x ppm Nitrate. The whole sample show 3.5 ppm - it means that I should take away 0.9*0.38 ppm from 3.5 ppm - giving me 3.15 ppm as result. But it was 10 times diluted - my tank contain 31.5 ppm NO3.

This method take some time but - it is the only method that have been working for me. First take a test of the water used to dilute with. Dilute 10 times - 9 dilution water 1 sample water. Take a new sample - read. Subtract 9/10 of the first result from the second result. Multiply with 10 - and you have X

Sincerely Lasse
 
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After using the EM bottle for Bukasha I noted a very high rise in NO3 - from below 5 up to over 50 during a two weeks. Not any large rise in NO2. The only explanation is that the solution I use was rich in NH3. However - i have a rather high rate of nitrification (at least I think so) I have stopped my dosing of EM and start to use the DSB as an denitrifier - and it works. Today I am around 16 mg/L of nitrate

Sincerely Lasse
 
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For the moment I dose ethanol (4%) below my DSB and have a weak flow (between 40 - 300 L/day) through it




1621954844495.png


You can see the result above . NO3 as reported by Hanna has decrease from around 50 (may 11) to around 11 today (may 25) - rather effective denitrifier. I manage the dose of ethanol and the reversed flow throw the DSB with help of a redox electrode - last day. light blue - my reversed flow through the DSB (ml*100) and deep blue - dose of ethanol

1621955819926.png



Sincerely Lasse
 

taricha

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What would you estimate that amount of ethanol is? could you translate to an approximate amount of vodka per day during that drop?
 
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Vodka around 48 %. I use 0.9 L 4% during this time - it means around 0,075 L Vodka -> 75 ml during 14 days -> 5.4 ml/day -> 310 L but injected there it is needed - below the DSB - not in the aquarium.

Sincerely Lasse
 

taricha

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Vodka around 48 %. I use 0.9 L 4% during this time - it means around 0,075 L Vodka -> 75 ml during 14 days -> 5.4 ml/day -> 310 L but injected there it is needed - below the DSB - not in the aquarium.

Sincerely Lasse
Thanks!
You're right. That's more NO3 decrease per ethanol "Bang for the buck" than you'd expect dosing into the water.
What process do you think is responsible for most of the NO3 decrease?
Classic (anaerobic) denitrification? Assimilation into biomass?
I ask because it sounds like you have decent flow of oxygenated water into the sand, and some strains are known to do denitrification in the presence of oxygen if they have a good C source.
Did you catch any NO2 showing up as the NO3 dropped?
 
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I think it is an classic denitrification - it follows all thinkable signs for that.

Nitrite - as normal

1622187505181.png


The decrease has gone further but it is a question about the Nitrat checkers result and my diluted samples when it goes down to measurements around 5. The last diluted sample show 16 but the same sample - non diluted show 5 - I have seen this before. Probably - a very small mistake will affect the reading very much - it will be 10 fold increased,

Sincerely Lasse
 
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