These 10-30 tetra internal filters are unusually quiet since the motor s under the water. Offering the same quality and performance as an external filter it ll function in as little as 2 of water allowing it to be used for turtle tanks or for creating a waterfall inside the tank. This Tetra whisper filter uses tetra s bio foam which eliminates toxic ammonia and nitrates that are not healthy for fish. Designed for aquariums up to 30 gals it s easy to adjust in high or low water levels with mounting suction cups and/or brackets. Each 30 gal fish tank filter comes with one whisper filter cartridge. This way you can get regular reminders to clean and maintain it simplifying the care process.