I don't have any experience with the Pondlife UV, but I do have a 36 watt Coralife. It works really well. But, the ballast on mine went bad after six months. Big Al's (where I bought it) replaced it for free minus shipping. They'll probably both do what you want. Be sure to factor in replacement bulb cost into your decision. It can vary greatly from brand to brand even of the same wattage.
If cost is a factor in picking a UV Sterilizer, Lowes has a 9 watt model for $60. I got one for my pond and it cleared up a horrible algea problem in less than a week. Replacement bulbs for that one are only $14 and are at Lowes also.
Slightly off/on topic but good info to know. I purchased a new Supreme Mag Drive 9.5 pump this weekend. I needed a longer cord so the guy at That Pet Place told me to check out the pond section as they are the exact same pumps but with 16' cords instead of 10' cords. The pump that has pond written on the box cost $10 less than the one that says aquarium.