I also found this on Reef Sanctuary:
1. Make sure the pH and temperature of the QT water is in the preferred zone (see below)
2. 2/3 Fill treatment container with water from QT.
3. Check and adjust temperature to below 80F. Hold it steady. If temperature is too high, chill it a little, by sitting it on a bed of ice.
4. Put on gloves and safety glasses.
5. Measure 1 ml of Formalin for every gallon of bath water.
6. Mix-aerate with airstone for 2 hours before using the bath; and during the treatment
7. Check pH and be sure it is between 8.0 and 8.4
8. Dim the lights
9. Capture fish in bag, drain excess QT water from bag, and let fish slip into bath with airstone running. (BEST to put only 1 fish through this at a time because of the shortness of available oxygen. Don't treat multiple fishes at the same time. BUT you may treat one fish immediately after another in the same bath, providing bath is controlled as noted)
. Start timer
10. Monitor fish closely. If fish stresses, it may still be okay. If you fear fish is dying, then abandon the treatment.
11. Leave fish in bath for 45 minutes (i.e. treat for 45 minutes)
12. Capture fish under water in bag
13. Return to QT (make sure there is another airstone in QT running OR a corner sponge bio filter running by air and circulating the water in the QT.
14. Monitor fish
15. On the second day after treatment, repeat the process starting with 1. and using fresh/new treatment bath. This will be the second treatment.
16. On the second day after this second treatment, treat fish again, starting at 1.
17. Repeat pattern (treating every other day) until fish has had 5 such treatments (but no less than 3 total).
18. Hold fish in quarantine for no less than 4 more weeks for observation to verify treatment has been successful.
19. Dispose of all bath water (and any unused Formalin) properly. That is, take it to a proper disposal site and follow disposal requirements of your national and local government.
20. When fish is deemed cured, throw away airstone and tubing.
