It involves setting up two QT tanks. Basic concept is you put your infected fish in QT tank 1 with fresh saltwater. On the morning of their third day in that tank, you remove them to QT tank 2 which also has fresh saltwater. You clean and sterlize QT tank 1 and refill it with fresh saltwater. On the morning of day 3 in QT tank 2, you remove the fish back to QT tank 1 and clean QT tank 2. You'd repeat this procedure for a total of about 15 days which should complete the life cycle of any ich cysts that are in the tank/on the fish. So, it looks like this:
Day 1 - fish in QT. Day 4 - in AM, but before tank lights come on (8-9 AM EST), transfer fish to new tank, matching temp and salinity. Transfer as little water as possible. Day 7 - repeat. Day 10 - repeat. Day 13 - repeat and done.
Make sure you sterilize all equipment used between transfers or you'll recontaminate. Most advocate not using nets to transfer, use a container with as little water as you can manage to move the fish from tank to tank.
One question: I understand that the cysts are very resilient. How do you do your sterilization to assure their mortality between QT's?
Most aquarists might be accustomed to cleaning their gear in vinegar...at most a 10% bleach solution, but that's pretty extreme for reefers. Do we know the minimum treatment that's sufficient?
Now, I have not tried this method myself, but i have read about it and considered the method so this is not first hand tested by me. That being said, I believe the key is making sure everything is completely dried between uses. It's thought that any cysts remaining in the tank or on equipment, once dry for 24 hours kills them.
You could use a mild bleach solution if you wanted as well, but it seems making sure everything is thoroughly dry is the key.