As suggested to me by an old timer, I have done a lot of product reading about all the new devices, b/c so much has changed since 30 yrs ago when I was young & had a ton of aquariums (under gravel filters and everyone believed in algae walls).
From dr.s Foster & Smith, I read:
http://www.drsfostersmith.com/fish-supplies/uv-sterilizer/ps/c/3578/4393
"UV (ultraviolet) Sterilizers are great supplementary devices for both freshwater and saltwater aquariums. Used in conjunction with your primary filtration system, UV sterilizers offer unique benefits from water clarification to effective management of various water-born microorganisms including free-floating algae."
And
http://www.drsfostersmith.com/pic/article.cfm?acatid=420&aid=1168
And
http://www.drsfostersmith.com/pic/article.cfm?acatid=423&aid=1315
And
http://www.drsfostersmith.com/pic/article.cfm?&acatid=423&aid=837
And
http://www.aquariumfish.net/information/uv_sterilization.htm
"is a safe and natural method to reduce waterborne pathogens and algae the causes “Green Water”. UV is as natural as sunlight. Unlike chemical treatments that can potentially harm the fish, beneficial bacteria, and plants in your aquarium or pond, UV does not leave any residuals in the water and therefore cannot harm fish and plants.
A UV sterilizer works in harmony with other essential filters by eliminating nuisance green water caused by waterborne algae that can easily create problems and ultimately reduce filter efficiency."
The second last paragraph quoted was in conflict with the " fish expert" video I viewed, but I believed he had other errors too, which is why I didn't post a link to bad info and wanted to double check what I had read with actual current aquarists.
