Just battled this myself and FINALLY won. It really depends on the type you have, but for me the only thing that got rid of it was blacking out my tank for 5 days and raising the temperature to 81 degrees from my normal 79. Is yours primairly on the sand bed or on rock work, does it disappear at night, what type of coral do you have in your tank if any? There is also a product called DinoX i was using while in the black out phase. I also started using Microbacter7 and stopped doing water changes while this was going on. Dino's seem to get a foothold in a tank when the water is to clean with Nitrates and Phosphates.
