The flow rates can be adjusted with the flow-control dial, and the flow can be redirected with the rotating outlet. To clean the sponge, simply wash it in a bowl of aquarium water, but NOT under the tap. Tap water will kill the friendly filter bacteria. Wash or replace one sponge at a time. Always read the instructions carefully before use. Tetratec IN 300 plus internal filter for aquariums up to 40 litres Key benefits are Improved venturi design that blows air bubbles into the aquarium without any loss of flow rate. This improves aeration of the aquarium, without any loss in filter performance. Split filter chamber that ensures each filter contains a minimum of two sponges. This allows one sponge to be cleaned or replaced, whilst leaving the other one in-tact. This helps to limit the loss of beneficial filter bacteria during maintenance, thereby maintaining water quality for your fish. Easy-to-clean design that allows the filter sponge and impeller to be removed without needing to take the entire filter out of the aquarium . This makes maintenance much easier. Flow adjuster that allows the flow of water to be reduced. This is beneficial for smaller aquariums, or those with fish that prefer a calm environment. Availability of two types of filter sponge. A combined biological / mechanical foam (TetraTec BF sponge) for removing ammonia and solid waste, and an optional carbon foam (TetraTec CF sponge) for keeping the water crystal clear. Because of the split filter chamber, you can have one of each for the best of both worlds. The carbon sponge is replaced every 4 to 6 weeks, whilst the biological mechanical foam is cleaned in aquarium water as necessary. Dimensions: 18 x 8 x 6 (cm). Power consumption 5watts.Water Flow 150 to 300 litres per hour.