In the formal language of economics, X and Y are substitutes if the demand for X increases when the price of Y increases, or a positive cross elasticity of demand.
Potting mix is the material that goes into a garden pot before you put seeds and plants into it. 1  It keeps the plant in place. 2  It holds water for the plantâs roots to soak up.  It contains nutrients that feed the plant.
In pool construction, however, the term shotcrete refers to wet-mix and gunite to dry-mix. In this context, these terms are not interchangeable (see Shotcrete vs. gunite discussion below). Shotcrete is placed and compacted at the same time, due to the force with the nozzle.