Me2,
I am mixing salts my self from singles so there's no real issues with adding them direct to the tank in their raw salt form. This is great for mixing a large res but for adding back to correct EC in a recirculating system that has a fresh water top off, a stock solution is by far more accurate/manageable/convenient..
Peace
BL
I wasnt knocking it Its not as much of an issue with Yara as they mill a lot of their dry mixes so they are well integrated. If you have a premixed dry nute that resembles multicolored gravel, its best to use the whole bag to make up the stock