all my fish have those white specs on them and i was wondering if i can quarantine the whole tank or maybe do the hyposalinity thing on the tank without removing anything.
You can do hyposalinity on your main tank with the fish in it, AS LONG AS YOUR TANK IS FO! If your tank has any LR, inverts, corals, then you can not do hypo in the main tank, as the hypo saline water will kill off coraline, LR, inverts.
Ich can live without a fish host for 6 weeks. So if your tank remains fishless for about 6 weeks then the ich will eventually die off. If the fish are put back into the main tank before the ich has died then they can become reinfected.