CRIM_miranswered grow question 4 years ago Thanks for the answers! At least two of the FF micronutrient products I use contain potash (e.g., Microbe Brew, Boomerang). Over the last week, the spotting has gotten worse, and now the lower leaves on my control plant look like they have a serious calcium deficiency. I fed them full strength micronutrients today, including CalMag Plus. I am hoping this helps.