.... dunno about Ca-Mg defc. affecting potency,...not likely, unless it's severe, chronic (ongoing), causing stress to the plant over time...that will affect potency, to what degree,... :dunno:...but a minor bout of it very likely won't, after all, it's those fan leaves that are sacrificed to supply the flowers with what they need... *** ...same deal with nute' burn,... if it happens late in flowering, make sure you give the plant extra time to cleanse itself and the soil of all those extra's, or flavor and smoke quality will definitely be adversely affected,...