@Alexz
At this point the only “reef safe” thing you can try is hydrogen peroxide dosing. Some corals and inverts might die. It’s the price you’ll pay by not having to do the extra work of removing fish. I think it’s a 6 month dosage time. You gotta be diligent with it and follow exact directions. This won’t remove all signs of the parasites. It will still be there but be kept at bay.
If you want a more proven method you need to remove all fish from tank and use copper, Hybrid TTM, or chloroquine phosphate. That’s the only proven treatments for marine velvet.