This fine-fiber filter wadding once again mechanically cleans the water before it is returned to the aquarium. EHEIM SYNTH removes the finest particles from the water, which are often responsible for turbidity in the aquarium. As a final layer of filter substrate, EHEIM SYNTH is used in thin layers up to 10 mm thick. Always use a new layer of EHEIM SYNTH after treatment with medication. To match your EHEIM outdoor filter, we also offer a filter cloth for the same purpose.