In a new tank, diatoms happen and people freak out. They’re short lived if you control your water quality (RODI). With zero phosphates, you are hurting the coral. But couple that with a mediocre LED and you’ll find it hard to keep all corals happy. Torch and other euphyllia are said to be really easy to keep by many but I’ve found that they are picky. Yes, they can do different types of lighting and flow but once they start to go, they don’t come back easily. Good luck with yours. It hasn’t bleached so you may be in luck.