Does the beneficial bacteria in a fish tank reside mostly in the filter keeping it safe from being killed by a uv sterilizer in a fish aquarium?

Answer 1

UV light kills whatever bacteria passes through it. Since there is no way to separate the good from the bad bacteria in an Aquarium, the UV filter must obviously kill good bacteria too. This will inevitably weaken the occupant fishes immune systems making them more prone to disease.

Answer 2

Yes, the aerobic bacteria that convert Ammonia firstly into Nitrite and then into Nitrate are mainly in the filter but they are also in the gravel and generally waterborn too. They are everywhere but their work removing ammonia is mainly done in the filter. There are however very many other bacteria that have an effect on the fish and subsequently their antibodies which in turn bears an influence on the fishes immune systems. We have inocculations/injections etc to put bugs into our systems in order to build up our immune systems to protect us. If we live in a sterile environment the first time we come across a bug we get very seriously ill because we have no antibodies. The same applies to fish in an aquarium. The use of an Ultraviolet device to kill ALL bacteria is a bad thing because it makes the fish have weak immune systems. Too clean is not good. UV Filters are an item that have been devised and produced and promoted with great "spin" to take in the unwary who have more money than scientific and biological knowledge. You will not find one in use in any Marine Biology department in any University nor are they in use in any commercial public Aquarium and those people have all the best equipment required.