What are UV sterilizers in aquariums used for?
UV sterilizers slowly pass aquarium water pass an ultraviolet (UV) bulb, which irradiates microorganisms like bacteria, algae, and protozoa. By damaging their DNA, it can shorten their life cycle and limit population growth. UV sterilizers do not seem to affect beneficial bacteria as much since that type of bacteria is mostly found growing in filters and on surfaces, rather that freely floating in the water column.
We like to use our UV sterilizers when dealing with green water. Green water is caused by tiny, free-floating algae and is actually very good for raising baby fish. Unfortunately, it also prevents you from seeing into your aquarium and can potentially block light from reaching your plants. Green water is fairly easy to treat, so you don’t need to get a very big sterilizer. The UV changes the cell structure of the algae so that it can’t reproduce. Once they’ve been sterilized, you can do multiple water changes over time to remove the green water, and soon enough your water will be clear again.
For more information on how to clear cloudy water, read the full article here.