Help on treating ich

[Sumfingwong]

My new DT has broken out into ich, probably from the kole and tomini tang I recently purchased.

I have a 55g I recently shutdown (not completely shut down, it has a heater and powerhead for the LR I am trying to sell)

I am thinking about setting up a 20g tank for all the small fish I have and treat them with cupramine. Then move the bigger puffers, foxface, kole and tomini tang to the 55 (move the LR out) and treat them with cupramine.

If I leave my 145 with the current LR, CuC, SPS and zoas with no fish. Can the ich die off? Or do I need to remove everything?

Thanks all