"nanoreef" wrote in message ...
By WS do you mean "white spot" properly known as Ick? If so that is
what killed your fish. The low temperature didn't help, but it was the
ick that killed the fish. Ick is a small parasite. It is hard to
control, and often fatal. Ick is the primary reason why reef keepers
use quaratine tanks.

Agree... it is hard to believe a reef tank can reach 18'C
with all the water movement devices adding to the heat...
Not even mentioning the lights during day.