# KNO3



## turtle (Jun 8, 2004)

How many drops of KNO3 (2 teaspoons mixed in with 167ml of H2O) should it take to give 9L of water about 5ppm of NO3? I think my test kit is stuffed as I have put 30 smallish drops in and the kit (Nutrafin) tells me it has less than 5 ppm! Could this be right?
David


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## gnatster (Mar 6, 2004)

2 teaspoons or approx 8.5g of KNO3 mixed in 167ml water will make a solution where 1ml or 20 drops will raise N level 3.54ppm so 30 drops would be 5.31 ppm. I'd check the test kit.


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## dennis (Mar 1, 2004)

Here is a great tool for plant tank enthusiasts. Many of us here use it when calculating our doses. The Fertilator located at the top of Aquatic Plant Central is also very nice Try them both. You might find it easier or more accurate to dose a more nominal size like 1 liter or 1 gallon, something along those lines. Also, grams are more accurate than tsp, which are simply a rounded estimate based on grams anyway.

For instance, 0.03grams KNO3 in 1 gallon H2O is ~4.6ppm NO3. 0.03grams is about .01 teaspoons. That is maybe equal to the amount of KNO3 you would need to cover an period in a regular newspaper article. You can see why it is hard to check with small tests You would be beter off dosing a 5 gallon bucket or something. If you know how much you add to your tank. Dose that amount and then test in 1/2 hour. HTH


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## Edward (May 25, 2004)

Use the Salt water colour table for the NO3 Nutrafin Hagen test. I tested it with standard solutions 0, 5, 10, 20 and 30 ppm, and it does read right on with the Salt water colour table.

Edward


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## turtle (Jun 8, 2004)

Thanks for the link, I think i may need to get another test kit. in the meantime Ive done some thinking and found chucks calculator, put it to use and came out with the thought that I would need a about 1ml of the KNO3 mix for 9L H2O and that would give me about 4.57ppm.

2 teaspoons ~ 11.2g KNO3 (chucks calculator)
11.2g KNO3 / 167mL = 0.067g KNO3 per 1mL of mix
so 
0.067g of KNO3 mixed with 9L H2O would be 4.57ppm by chucks calculator

simple I thought. Wrong  
if i use the math that Rolo used at this post
http://www.aquaticplantcentral.com/forum/viewtopic.php?t=2621
and modify it to this

Molar mass KN03 = 101.1g 
Molar mass N = 14.0g

For 1L H2O
0.033g KNO3 x (14.0g/101.1g) = 0.00457g N = 4.57 mg N 
1000mL = 1L 
4.57mg/L = 4.57 ppm N

So for 9L H2O
0.033g x 9 = 0.297g 
0.297g KNO3 in 9L = 4.57 ppm

That's 4 or 5 times as much as chucks calculator states :shock: !! Where am I wrong?
Turtle


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## Edward (May 25, 2004)

You forgot about Oxygen to include in your second calculation. We test for NO3, not for N.

KNO3 -> (38.7% K, 13.9% N, 47.5% O)

61.4% of NO3 in KNO3

There is nothing wrong with the Hagen Nutrafin NO3 test. I tested Aquarium Pharmaceuticals NO3 kit and found the same thing. The Salt Water colour table is right for fresh water measurements.

Edward


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## turtle (Jun 8, 2004)

A slight over look on my part  thanks for the help edward it is greatly appreciated, i will do a controlled test with the kit now that i have some idea of what it should take to get 5ppm, no doubt it will be right [-o< 

David


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## gnatster (Mar 6, 2004)

> 2 teaspoons ~ 11.2g KNO3 (chucks calculator)


and in my post I said



> 2 teaspoons or approx 8.5g


Edward and I were discussing this in chat and I went and weighed a tsp of KNO3 10 times using a standard kitchen measureing spoon set. The avg of 10 seperate entries was 4.34g. That comes to a bit more then 1 gram less then Chuck's.

Just a point of reference


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