UV sterilizer for sale that's good for pond or aquarium usage up to 10000 litres water volume. This UV sterilizer has an 11 watt UV light.
Where do you install the UV sterilizer? Before or after the filter? Well it needs water pressure to run, so in most cases the UV goes after the pump and before the filter. If you put it after the filter then there wont be enough pressure.
Here is a basic diagram: