I will have to disagree with the concensus so far. I would NOT use the UV
sterilizer during cycling. Any living thing that goes through that sterilizer will die, be it algae, diatoms, or BACTERIA.
It is true that the majority of the bacteria is found in the filter/substrate/and glass but the bacteria first has to get to those places to colonize. The only way this happens is by some free floating bacteria attaching to these areas. Having a UV
sterilizer in use will kill any beneficial bacteria that flows through it, slowing your cycle (though to what degree is debatable). I would hold off on using it until you have cycled and added fish.