All the fish in my friends reef tank are covered in ick. The last fish added was 6 months ago and he quarantines all incoming fish and corals. The only new additions are a dozen astrea snails recently purchased from an LFS. The ick appeared within a few days of adding the snails ( no snial water was added) He noticed later the LFS did house the snails in fish tanks. Is it possible that the snails are a carrier of ick ? What other source could it be?