I don't know as much as the rest of the guys here, but if you have no fish, I would say drain the entire tank and wash both it and the gravel with a strong solution of non iodized salt. Then I would let the tank sit dry for a week before even thinking of using it again. Maybe they could offer you better advice, but that's what I would do, just to be safe.
Or possibly you could treat the water with a strong dose of Pimafin and raise the temp up real high for a week or so. I thought someone here said ick won't survive over 85 degrees -- that is, if you are sure it was ick.
Other than that I am curious myself what the others here might suggest.