I went to Petco tonight, and they had other types of Iodine for treating reef-type aquariums. The Iodine they had for sale was not Lugol's, so it was not good to take.
"Kent Marine" is one brand that sells Lugol's for aquariums.
"Niles" is another brand people on this forum have used successfully, but "Niles" might not be the complete name.