Instruct: Classify Amazon reviews into positive or negative sentiment
Query: A little disappointing

I hoped it would work in my small aquariums, but it did not. I guess the water levels weren't high enough? I have no idea why it was not able to vacuum anything out, but it would've really been useful and a convenient tool had it worked since I got it so that I wouldn't have to do a full water change so often or use a siphon on such small tanks. It did work okay in my full size tanks.