When I got my blue tang I asked the same question. I thougt about doing a preventative hypo treatment as that is less stressful. After reading the responses here I chose not to. Like Kurt I watched it. When I saw signs of flashing on day 4 thought om here it goes. I started the clock over but nothing developed. A daily pwc
with vacuuming the bare bottom might have helped, but I'm not sure. The tang has been in the main tank for several months now.
I tried to QT some corals but they started to wither under just pc
lights. Now I temp and SG
/pH acclimate, rinse and swish in tank water (in a bucket) then place in the tank.
I used to buy fish from a lfs
that treated all FO
tanks with copper. Never had a probelm with any fish I got from them them. Too bad they went under.