Five Oceans 1-Inch - 1 1/4-Inch - 1 1/2-Inch Check Valve Stepped Connection, Boat Bilge Pump Non-Return Check Valve, Marine in-Line One Way - FO2056

I bought this valve to prevent back-flow into my bilge after the float switch shut off the bilge pump. The back flow from the rather long discharge hose would raise the water level, closing the float switch again and the pump would endlessly cycle. This check valve holds back the back flow, and prevents the cycling. The valve does not leak, and the pump does not cycle even after several hours.

Initially this check valve worked fine, preventing backflow to my aquarium sump during power outages. However I noticed a few weeks later that it didn't work every time. Now after a few months it doesn't work at all. It allows water to flow in either direction freely. I initially thought it was because I mounted it horizontally, which I know you have to be careful about with flap type check valves, so I changed it to vertical. That didn't help. It could be that I made a mistake, perhaps too much back pressure, or some debris is blocking the mechanism. I will be replacing it soon with a clear unit allowing me to see what's going on inside and if I did something wrong I'll adjust or delete this review. For the moment however I can't recommend this product.