Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Tetra Whisper In-Tank Filter 10I with BioScrubber, 3 to 10-Gallon

I have 2 of these each one is in a land water terrarium, 1 of the units is in a tank that only has 2 inches of waster at the bottom and the other is in a tank with about 6 inches of water in it.they are both 55 gallon long tanks.my only annoyance is in the tank that only has 2 inches of water, when the unit was new it had more suction so when the water evaporated and dropped below 2 inches it would still function, but now at a year of ownership their is a noticeable performance drop.but I suppose that is to be expected.other then that they work great.