Uhh...I wouldn't say that they will help reduce the population. They may luckily catch one or two that happen to wander too close to the tentacles...but that's about it.
Most pods in reef tanks are beneficial scavengers. Their population will increase and decrease as the food supply changes. If, for some reason, you want them gone, then the easiest thing may be to limit the food you add in. Of course, various fish (like wrasses) will go after them as well.