SPS Growth Puzzle

[Nebthet]

I would suggest to raise you calcium (if your Mag remains 1400 do that, but perhaps suppliment a little once a week to help. Tests can be off).
Also use something like CoralVite and Coral Accel once to twice a week about two to three hours after lights out or first thing in the morning when polyps extension on your sps should be at it full extent.

When I started doing this with my SPS (and I use tapwater in my tank) I finally saw growth in my frags that had no growth for a year, not even encrusting. Now all my sps grow nicely.