It can take a couple of weeks or more for a coral to show any outward appearance of struggling that started weeks prior. Often with a coral like this that is not looking happy you don’t look at what was happening currently but look back at weeks prior for changes, swings that may of occurred. I’m still standing by this is going to turn for the better but just like it can take weeks to show decline it can take weeks to return to 100%. Let’s assume this all started from the sand irritation and you implemented changes as mentioned. Follow
@vetteguy53081 ’s advice and maintain your nitrate at 10-15 and phosphate at .05-.1. Your calcium is good so make sure your magnesium is above 1350, they tend to thrive with it at 1400 or a little higher. Keep it in moderate flow and light and you should start seeing the improvement you are looking for.