Do you have silica? I use dynagrow protekt, it says it helps with heat, drought and cold. It also brings the ph up, depending on what kind of h20 you use. What I do, is fill a 10 liter bucket up and put plastic wrap over the top so it doesnt get shit in it. Let it sit for 24/48 hour, I use 3/4 tap 1/4 bottled usually, add protekt and ph end up around 6.7. If I use more bottled, itll lower the ph if you want to let the ph shift a little.
i use calimagic for my cal\mag as it is 1-0-0 opposed to others that have more nitrogen which you dont want too much of in flower I guess. I havnt used it in the last 5 feeds, only when necessary.