In this hobby,we always need to be on top of things,I thought i was doing everything correct.Made sure temp was the same,also alk,cal.But over looked some very small die-off from rock.Had a few corals react to it.I hope ones who are up-grading look at this thread,because, the tinyest dye-off on live rock seems to effect corals.I will know next time,because this new 180 is way to small,LOL.Should off went 8 ft long and 36" wide and 27" tall.