Nitrate in GFO

Dan_P · 01/30/2017, 06:17 PM

I found that stirring 0.5 teaspoon of Phosban in 20 mL tank water (NO3 not detected) produces a nitrate level of at least 100 ppm by the Salifert test kit. A second 20 mL rinse of the same GFO results in only a 10 ppm rise in nitrate level. I have not ruled out the possiblility that the contaminant is nitrite.

The upshot is that 0.5 TSP of unrinsed Phosban would raise the nitrate level in 50 gallons by 0.01 ppm. If I am remembering my measurements correctly, 1 ounce is 12 times 0.5 TSP, corresponding to an increase in the nitrate level by 0.12 ppm. Half a cup, ~0.5 ppm.

Rinsing GFO with distilled water produces similar results.

Interesting?

bertoni · 01/30/2017, 07:25 PM

I wonder whether there's interference of some sort at play, but that seems unlikely. I wonder how the nitrate got into the mixture.

Dan_P · 01/30/2017, 08:22 PM

Quote:

Originally Posted by bertoni

I wonder whether there's interference of some sort at play, but that seems unlikely. I wonder how the nitrate got into the mixture.

High levels of Fe2+ reduce the amount of nitrate detected. I couldn't find anything on Fe3+ interference.

01/30/2017, 06:17 PM	#1
Dan_P Registered Member Join Date: Aug 2014 Posts: 1,432	Nitrate in GFO I found that stirring 0.5 teaspoon of Phosban in 20 mL tank water (NO3 not detected) produces a nitrate level of at least 100 ppm by the Salifert test kit. A second 20 mL rinse of the same GFO results in only a 10 ppm rise in nitrate level. I have not ruled out the possiblility that the contaminant is nitrite. The upshot is that 0.5 TSP of unrinsed Phosban would raise the nitrate level in 50 gallons by 0.01 ppm. If I am remembering my measurements correctly, 1 ounce is 12 times 0.5 TSP, corresponding to an increase in the nitrate level by 0.12 ppm. Half a cup, ~0.5 ppm. Rinsing GFO with distilled water produces similar results. Interesting?

01/30/2017, 07:25 PM	#2
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	I wonder whether there's interference of some sort at play, but that seems unlikely. I wonder how the nitrate got into the mixture. __________________ Jonathan Bertoni