Ok so my 10 gallon nano with a Noopsyche K7 V3 light, Ice Cap ATO, and chiller had a die off of a few corals seemingly out of nowhere that started a couple months back and now seems to be done (as in the affected corals are dead while the unaffected ones weren't affected at all). The tank was about a year old and didn't need to dose as parameters were kept in check by frequent testing and water changes. The only thing that did cause a sudden fluctuation was the addition of a new fish which caused a spike in my nitrates and phosphates due to his diet of grindal worms but after removing him and getting things back under control, a few corals kept dying (an acro, Monti Cap, and pocilloporra which were previously doing well). My two Digis made it fine and even showed growth along with my Crocea clam and inverts were fine. Should I start to slowly add back corals now (SPS but no across until I feel comfortable again)? Or what should I do? Alk, cal, nitrates, mag, phosphates, are where they should be at the recommended levels and seem stable as it's a fishless system now. What should I do?