Sorry to hear man. It was brutally hot last week and event he week prior. Reefing in Calgary can be quite challenging. It's brutally cold in the winter (minus 30 or below), and can be brutally hot in the summer (plus 30 or higher). Curious if you had implemented any cooling for your tank ?
ya, if your corals are white due to colour loss only, that is, they still have flesh on them, then they can definitely come back.
However, if they've lost all their flesh then they are done
Snap some pics and post them here if you're unsure. We can help you evaluate.