As already mentioned, ozone is a very good degermination or sterilisation agent, and the redoxpotential is an indicator of the degree of degermination. While at a redoxpotential of 200 mV 100 % germs exist, the formation of germs is reduced by increasing the redoxpotential from 200 mV to 300 mV, e.g. by 90 % to only 10 % of the formation of germs at the beginning. If the redoxpotential is increased to a value of 400 mV only 1 % of the original germs exist. This definitely shows that redoxpotentials exceeding 400 mV are not necessary for aquarium systems. Absolute sterility is achieved at a much higher redoxpotential of 700 mV. But this is not recommendable for aquarium-systems and can not be achieved with common aquarium ozonizers. Especially for fresh water systems with water plants or for salt water systems with invertebrates a lower redoxpotential of about 300 mV is favourable.