Potassium nitrate npk question

[71xlch]

Hi,

Here in Canada potassium nitrate is hard to come by. I found some at a hydroponics store. It's labeled as potassium nitrate with a npk of 13.5-0-46. Online sources indicate it should be 13-0-44 when pure. The stuff I have is a pure white crystalline solid, in fine grains. Just wondering if Randy or anyone has some insight/comments?

Thanks.

 

[Reefing Madness]

 

[Randy Holmes-Farley Verified Community Expert]

I expect it is either just a rounding error, or a moisture difference. I wouldn't rely much on those sorts of numbers.

 

[Stigigemla]

The potassium nitrate can contain some anti clumping agent. I buy my potassium nitrate from a fireworks shop and they have both anti clumped and pure. I guess Randy might know whats in it.