Tank is crashing :(

[MitchM]

Your tank setup looks fine, but your tank has been through a lot of changes in the last 6 months including light changes, changing from dosing to a calcium reactor, alk fluctuations and the use of carbon dosing plus you have a mixture of lps and sps. You didn't mention if you were using activated carbon, so that may be a good idea to compensate for the allelopathy (chemical warfare) between your corals.
Bottom line I think your tank needs some stability, but start with a regular water change schedule.
Turn down the lights and increase water circulation. Water circulation is as important, if not more important than lighting.
imo