Amazon Customer 5 What I use this product for: I had a persistent "green water" problem in my aquarium. I tried chemicals (did not work), 100% water change (works but revert to original after 3 days). Then I saw the reviews here what this device can do. I had my doubts. So I researched by going to other aquarium maintenance sites. I finally bought this (expensive!) grudgingly.What works: It simply just works! Look at the photos after 4 days. The UV lamp has an enclosure so it is safer than without it. Quick delivery which took out my anxiety looking at my aquarium every day waiting for the device to arrive. I finally see my fish again!What does not work: Expensive! Too may wires to figure out. No idea how long the UV lamp will last. Motor pump is loud sometimes depending on how the wires are positioned. No idea how water resistant it is. It could kill my fish. But they are still alive so far.