My question is what is the process to do a bath on rally, I know that doesn't solve the problem but it is part of the process to eradicate the problem.A rally dip alone won't cure velvet (Amyloodinium). It is used to just get a jump start on the disease progression. You need to eliminate the dinospores from the tank itself, else the fish will continue to get reinfected when you return them to the tank. If you have fish and invertebrates mixed, there isn't a good solution other than moving the fish out, treating them there, and then letting your invertebrates live in a fishless tank (no disease host) for a period of time so the diseases die out. A FW dip, moving to a clean quarantine tank and then dosing with copper is the best course of action. If you truly have velvet, you need to act very quickly, as this disease kills rapidly. Velvet is fairly rare, and many people confuse it with late stage marine ich though.
Jay