corals in trouble

[MCC]

hello,

i was wondering how come some of the corals do not seem well....
espeically the mushrooms and colt coral....

it was fine yesterday but they r not expanding at all...and the colt coral is slanted on its side??!

this all happen after i put in a blue tang....

i tested the water..and the parameters seem fine...the salinity is at 1.022-1.023

i have weekly dosing of calcium, iodide, vitamins, and phytoplankton

lighting is from a 175watt metal halide with two 30watt atinics...on a 33 gallon tank..

can anyone tell me wat is happening asap

thanks...