I treated all my acros when I switched tanks a month ago. I took everything out of the old tank except the acros, and did a 24 hr treatment before adding carbon. I left the new tank without acros for 5 days as Borneman suggested. So far after 3 weeks I have no re-infestation. I would treat the whole tank only as a last resort, if you can't get your acros out easily.
Your really going to like the results after you treat. The effect on the acroporas is almost instantaneous.
This is a picture of a frag taken about 2 months before the treatment, which is how it still look just before treatment.
And 2 days after the treatment. I know it's hard to see with the white background, but if you look closely you can see increased polyp extension and color improvement.
