There are many reasons why people choose to build a pond on their property. In fact, it is a dream of many homeowners to have one. Chances are, you might have heard of check valves. Why are these valves needed for pond construction? This type of valve is designed to help external pumps retain their prime. Check valves also prevent water from completely draining out of waterfall filters when you turn off the pump. At Everything Koi, we offer a wide variety of pond installation and maintenance supplies, check valves included.