What are my params telling me..?

[Mr.Firemouth]

Catch22, it is imperative to test for Alk, CA, and MG at a minimum.
If Alk drops or Ca is too low your tank will lose corals.
You will only know by testing.
If you wait for your corals to tell you they may be damaged beyond repair.

Sub,
Test for PO4. Big reason for the browning in most cases.
Rich