I did peroxide for a while. It did work with some dinos, but I think it just made other things die, which led me to more problems -- and eventually, more dinos. The only thing that actually killed them for me was raising my mag very high-- and then, it caused a ton of other stuff to die, which led to a complete hair algae outbreak. I ended up sick of the nearly 2 year battle and just took all the corals off, put them in a holding tank, did the same with live rock, and removed all the water and sand from the system. Was a lot of work, but I'm finally back to really enjoying my tank.
I did everything, raised PH-- lights out for up to 4 days, high alk, manual removal through a filter sock, water changes, no water changes for a while, every chemical in the world, etc etc. They always found their way back eventually. Never dealt with anything more frustrating. Hopefully yours is gone.