IME if you add anything to IO unless it is magnesium first, you will get precipitation on the bottom of of your mixing container.
Then you wil not have the levels you want in your water, you are just adding to junk at the bottom.
I found I could add calcium all day long and it would never get above 350-375.
Now, add 180 ppm of magnesium first, then you can add calcium and have no problems at all.
