what are impurities?

[ddc0715]

I hear this word alot from people that do not want to use cheaper chems like soda ash and ca substance not bought from a lfs or online reef store.

what are these impurities? why does this word pop up alot? with no proof they impact anything. calcium cholride is calcium cholride is it not? what am I not understanding. thanks.

 

[Randy Holmes-Farley Verified Community Expert]

calcium cholride is calcium cholride is it not? what am I not understanding. thanks.

No, it is not. :)

Impurities are, by definition anything you do not want, but when I analyzed several commercial and DIY brands of calcium chloride, there are many other elements present, including some you would not want at sufficiently high levels (e.g., cadmium).

https://reefs.com/magazine/aquarium-chemistry-purity-of-calcium-chloride/