Weird stuff in Seachem kalkwasser

[starfishguy869]

I recently bought a fresh tub of seachem kalkwasser and when I was mixing it up, I saw something weird sinking at the bottom of my container, they were weird black specks that resembles sand (picture below). I decanted the liquid off and poured the specks into a measuring cup. When pure hydrochloric acid was added, the solution turned green and I could tell that my kalkwasser wasn’t pure as when pure calcium hydroxide was added to hydrochloric acid, it should be clear. Are these specks normal?

After addition of HCl:

 

[starfishguy869]

Also please correct me if I’m wrong.

 

[TX_REEF]

I have never seen any black specs in the kalk powder I use from BRS, for what it's worth.

 

[starfishguy869]

Ok thanks.