Aqua UV 8W Advantage 2000 HOB UV Sterilizer
Product Review (submitted on August 29, 2010):
To all the naysayers out there who say a UV is optional, they probably never used one.
My 100 gallon tank had perfect water when I tested it but there seemed to be parasites causing white ich on my longnose butterfly and blue tang. Unfortunately, I did not get this UV before my longnose butterfly, two clowns, and a royal gramma perished within a week of buying them. My blue tang was on the decline and getting more ich covered each day in the 3 days I had him UNTIL I installed the UV sterilizer then in a sudden turnaround, he got better each day with fewer white ich on him and after 4 days of UV so far, he's almost fully recovered.