Calcium and Magnesium Deficiency in the Bud Stage

I will say this is my first hydro-grow and have I learned a lot. I had one ph fluctuation problem right off the bat. (When I first filled my reservoir I had it ph-ed, but I think the additional water added from the storage tank threw it off overnight. When I checked it in the morning, it was way low, out of my range. This caused a little bit of burn on the older growth, but nothing too serious. About week 6 of bloom I started to see some rust spots overnight. Not enough cal-mag. Hey, I'm learning. One thing I've learned about Hydro vs. soil is that Hydro seems to show signs faster than soil and can be corrected just the same. It seems like soil; once you fall off the edge, it's hard to un-fall.