For use in an outdoor pond. Is a UV sterilizer light the same as an ozonator. Is ozonator same as ionizer?

Question:Used supposedly to kill algee etc.

Answers:
No. :)

Sorry for the short reply, but all three are different.

A UV sterilizer is simply an ultraviolet bulb in a housing that water passes through. As the water flows around the bulb (encased in a quartz glass water jacket), the UV rays sterilize or otherwise mangle the DNA of the small organisms exposed to it. In other words, if it can get into the pump for the UV sterilizer, it can be damaged by the UV rays. Algae fit this bill and if the UV bulb/pump combo is appropriately sized, can do a great job on algae in both ponds and in aquariums. Bigger is generally better, but matching up the bulb wattage and the pump rating is a good way to go.

Ozonators are totally different, basically generating ozone and injecting it into a captive water stream. The ozone molecules are powerful oxidizing molecules and again attack organisms small enough t be passed through the pump supplying the ozonator. Again, if properly sized, ozonators can do a good job at reducing algae and bacteria in a pond or aquarium. In this case, too much can be bad since the ozone can be dangerous to fish and other organisms you're trying to keep.

Ionizers are a separate thing -- I'm not sure you can actually use one in a pond or aquarium. They create acidic water, which is then corrosive/oxidizing to living organisms. The problem here is that it doesn't break down very easily (or at least not as easily as ozone) so there is a potential of this acidic water reaching the inhabitants of the pond/aquarium.

Of all three, your safest, easiest, and cheapest bet is to go with UV sterilizers -- they are well established in the industry and have been used for years. Lots of supplier should be able to help you find the right mix for your situation.

Hope it helps!