I highly recommend testing Alk (KH) and Mg as those are very important to monitor with LPS and SPS. Swings in Alk can cause a lot of stress to your coral. If you have had it for 6 months and it’s suddenly not looking well I would suspect it’s nutrient/element related. Your phosphates are also a little lowI currently don't have an alk or mg test. My Ca is around 420.