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Hello. I have a question that causes me an existential crisis.

What is the correct way to interpret the NPK ratio? It will refer to:

1. N (nitrogen) - P (Phosphorus) - k (potassium)
2. NO3 (nitrate) - PO₄³⁻ (phosphate) -K + (Potassium)

for example: I want to abonate in such a way that my NPK concentration in the aquarium is 10-1-13. the N concentration of 10ppm will refer to the concentration of nitrogen or nitrate, since if it is in relation to nitrogen, I will have to dose more nitrate to comply with the nitrogen dosage.

I have made my inquiries but I have not had a definitive answer on what is the correct way to interpret the nutrient dosage. and this is important since I do not want to misinterpret the information and with this I do not cause disaster in my aquarium.

Please reason your answer

Regards
 

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Hello. I have a question that causes me an existential crisis.

What is the correct way to interpret the NPK ratio? It will refer to:

1. N (nitrogen) - P (Phosphorus) - k (potassium)
2. NO3 (nitrate) - PO₄³⁻ (phosphate) -K + (Potassium)

for example: I want to abonate in such a way that my NPK concentration in the aquarium is 10-1-13. the N concentration of 10ppm will refer to the concentration of nitrogen or nitrate, since if it is in relation to nitrogen, I will have to dose more nitrate to comply with the nitrogen dosage.

I have made my inquiries but I have not had a definitive answer on what is the correct way to interpret the nutrient dosage. and this is important since I do not want to misinterpret the information and with this I do not cause disaster in my aquarium.

Please reason your answer

Regards
Typically we don't fertilize based on pure NPK ratios but by following a fertilizer regime. The reason is that 1) it can be hard to accurate numbers for some of these values in aquarium water, 2) they don't take into account micros which are also important, and 3) its SIGNFICANTLY easier to go with already established methods. The two most popular types are EI and PPS-PRO. There are other regimes but those 2 probably make up the vast bulk of all planted tanks. Most of the all in one bottles are actually EI. Do some searches for these two methods and you will find quite a lot about them. Good luck!
 

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Hello. I have a question that causes me an existential crisis.

What is the correct way to interpret the NPK ratio? It will refer to:

1. N (nitrogen) - P (Phosphorus) - k (potassium)
2. NO3 (nitrate) - PO₄³⁻ (phosphate) -K + (Potassium)

for example: I want to abonate in such a way that my NPK concentration in the aquarium is 10-1-13. the N concentration of 10ppm will refer to the concentration of nitrogen or nitrate, since if it is in relation to nitrogen, I will have to dose more nitrate to comply with the nitrogen dosage.

I have made my inquiries but I have not had a definitive answer on what is the correct way to interpret the nutrient dosage. and this is important since I do not want to misinterpret the information and with this I do not cause disaster in my aquarium.

Please reason your answer

Regards
Generally speaking, when someone mentions their N/P/K dosing, it would follow your example 2. above. As a reference, my WEEKLY N/P/K would be 16/6/18 using individual salts (MgNO3 & KH2PO4 in my case). This is also based on 75% weekly water changes and front loading macros after the water change. I mention all the extra information as it does pertain directly to one's dosing.
If you only do 50% water changes weekly, there will be extra accumulation in your tank which typically would result in less macro's being added.
Hope this helps a bit.
 
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In the US, "front of the bag" NPK fertilizer amounts are given as available nitrogen (N), phosphate (P2O5), and potash (K2O), even if those forms are not actually in the fertilizer itself. There are conversation factors based on molecular weight that you use to translate the salt you actually used to this format. As @Mark Fisher said, multiple nitrogen-having ions get grouped together.

This is the standard that gardeners and farmers understand, but in this hobby we tend to think in ppm of the ions of interest. Ammonia and nitrate cannot be combined because their effect on the tank overall differs.
 

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@Markovzky
first of all you will naturally find that nitrogen is normally present in the aquarium even if you didn't add any Nitrogen, Phosphate is also present if you are feeding your fish/shrimps.

10-1-13 NPK ratio is 44.19 ppm NO3 (if all of it is in NO3 form), 3 ppm PO4, 13 ppm K if you prefer using this term. but keep in mind that most of these ratio are based on combined numbers of Nitrogen from Urea, NH4NO3, KNO3 etc. if you were to add 44.19 ppm NO3, then you are also adding 27.9 ppm K. so this ratio only using KNO3 and KH2PO4 would look something like this: 10-1-29.1 (additional 1.23 K coming from Kh2PO4).

if your main goal is to add say 10 ppm NO3 (2.26 ppm N) using KNO3 then you would select 10 ppm NO3 or 2.26 ppm N, which will add 10 ppm NO3. if your goal is to add 10 ppm NO3 using NH4NO3 then you would choose 2.26 N which will add 5 ppm NO3 and remaining in the NH4-N form. same thing apply to Urea, if your goal is to add 10 ppm NO3 using urea, then you will select 2.26 ppm N, which will add 10 ppm NO3 if all of it is converted to NO3.

you cannot achieve 10-1-13 N-P-K ratio only using KNO3 unless you add something like urea to it. you will add 18.65 (4.22 N) NO3 from KNO3 and 5.78 N (25.54 NO3) from urea to achieve this ratio.
 
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