Number in Dry Chemical

[Steven]

Hi,

Does anyone know that the number below the dry chemical means? Eg. KNO3 I bought from Aquarium Fertilizer read 13.5-0-46.2, KH2PO4 0-51-34 and K2SO4 0-0-50. Thanks.

 

[nipat]

It is percentage of N-P-K.
The 13.5 is from only N, not NO3, BTW.

KH2PO4 should be 0-52-34, probably a typo.

More info can be found here (in "Macronutrient fertilizers" section).
http://en.wikipedia.org/wiki/Fertilizer

 

[Steven]

Thank you nipat and I've edited the KH2PO4 that read 0-51-34 so, it means 0% (N), 51%(P) and 34%(K) in KH2PO4 powder? Thanks for the great link too.

 

[nipat]

so, it means 0% (N), 51%(P) and 34%(K) in KH2PO4 powder?

Yes, in a sense. They use a different method in counting.
N is N, P is P2O5 equivalent, K is K2O equivalent.
I found a better explanation: http://www.oldhouseweb.com/gardening/analysis-or-fertilizer-grade.shtml

For planted tank, we count them by molecular weight instead.
With this method, the KH2PO4 is 28.73% K, 69.79% PO4.
http://www.convertunits.com/molarmass/KH2PO4

 

[barbarossa4122]

I did wonder what those numbers are, now I know. Thanks.

 

[Wet]

Great molar mass percentage calculator: http://stud1.tuwien.ac.at/~e9125168/javas/jmolar.html

 

[Steven]

Wow, thank you all and will bookmark the sites for future reference.