KCl math and MgCO3

[AFHokie]

I got some food grade potassium chloride for my reef to get potassium up a tad and want to double check my math. Seems simple but want to make sure I’m not missing something before I nuke my tank.

Approx water volume 20 gallons. Rounding that down to 75 liters as I’d rather under dose a bit.

Label says per 693mg KCl there are 363mg K.

Assuming I dose 693mg of powder I should get a net K increase of approximately 4.8ppm, right?

363mg/75L = 4.84 mg/L ≈ 4.8 ppm

Also, the bottle says there is 0.5% MgCO3 as a flow agent. Guessing that will do nothing more than add a negligible amount of Mg to the tank? About .04ppm if the math checks.
Anything else to worry about with the MgCO3?

 

[Dan_P]

I did not check atomic weights, but calculations look right. MgCO3 should not be an issue.

 

[Randy Holmes-Farley Verified Community Expert]

I agree magnesium carbonate at small amounts is no concern.