it needs just as much Ca in flower as vege. so if you did make a recent change, it is possibly related.
bit early to be certain. looks a bit overly lush though in general. This doesn't look to be off of either of the 2 current diaries? But looks like you are soilless/hydro context, so...
Ca greater than 100ppm is good.. may need more. That would the total of what you add in your fertilizer mix, not just 1 product. Part of a 1.3-1.5 EC overall concentration, give or take. If giving more, chances are something is building up in the plant, which can also impact availability of other nutes.
If giving 100ppm or more consistently, and these problems more clearly discern t hemselves as Ca-related, it could be from too much of something else. If pH is too low, similar situation where you might have plenty of Ca but availabilty is constrained due to low pH
diagnosing stuff is always a bunch of maybes.. cross-reference what you know and make the best decision. if those spots are on very few leaves, i'd wait a second before reacting in any drastic fashion.
+1 strain
