problems with millaporas

[MitchM]

Your lighting is good, your flow is possibly sufficient, depends on how you have it arranged.
More water flow would be good. Flow is more important than lighting for corals.

I would be concerned that maybe you have some alleopathy (chemical warfare) going on, and with very few water changes plus no carbon, any new corals will have a hard time adapting.
Rowaphos can be hard on sps if you're using too much. How much are you using, and have you always used it?
The pictures might help a bit more.