hello, I just started my first reef tank 3 months ago. 60 gallon tank with a canister filter, I have a sumpless ATO, 2 vipar spectra lights at 30% and an rp-m v2 power head. I have have my temp set to 78 degrees Fahrenheit. I added my first corals about a month ago, ive started with finger leathers, toadstool, hammers, and pulsing xenia. everything looked great and I had quick growth with the xenia. all of a sudden over night I had all my corals showing skeleton or completely closed. All five of my fish died. I had 2 ocellaris, cherub angel, tailspot blenny, and possum wrasse. took a water sample to my local reef store, was told my water was near perfect but alkalinity was a little low. they have no idea what went wrong. was recommended to ad carbon to my filter and do a 30% water change. if anyone has any ideas on what happened or how to move froward I would love to hear it.