Why does a UV sterilizer have a maximum flow rate?

The amount of time water in your aquarium is exposed to the UV bulb will determine the effectiveness and use of a UV sterilizer or clarifier. This can be directly adjusted by the flow rate, which determines how much water flows over the bulb and for how long. The longer the bulb is exposed to the water, the more thoroughly it can sterilise the water. This can be used to address free flowing algae issues (green water), parasites and bacteria.

Depending on the reason you are using a UV System, you may need to increase or decrease your flow rate as this will determine to what level it sterilises. If the rate is too fast, the bulb will not have the time to actually clean and sterilise any possible components that may reside within the water column.