Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Penn-Plax Super Battery Vac

This is a good little vacuum for your aquarium. It's battery operated (2 C's) and it's small enough to get between rocks or other objects. We've used this item several times. The little catcher bag will fall off if you don't have it clamped tightly on the vacuum. My husband usually just holds it with his hand, but I think you could just put a rubber band on it and that would be fine. Anyway, this little vacuum does a good job and we've used it quite a bit since we bought it.