another vote for the pepperment shrimp. sump is full of aiptasia, display is free of aiptasia. i have kept peppermint shrimp in there for about a year. sometimes i think they have all died but they show up again. bonus, they are always producing eggs that their tank mates find very tasty. i finally added one to the seahorse tank as i tired of aiptasia hunting and surprise! no aiptasia. get'em.
I have heard that the Golden Coris Wrasse, (which is not really a coris) will eat the flat worms.
clint - get 2-3 of the peppermints, they are great night time scavengers and will keep the tank really clean. i read only one account of them hassling clams, i have never seen this repeated anywhere though.