Description

These one way valves can be used to prevent water from "backflowing" when a pump is turned off and/or to help in keeping an external pump "primed". Make sure that valves that are installed horizontally are positioned so the internal flap's connection to the valve is at the top, not on the side or bottom. This helps the valve close all the way. Here are (2) examples of when and how to use a check valve.

Example #1: While cleaning your skimmer you should turn your pump off to keep debris from being drawn into the pump's intake. When the pump is turned off, water and debris from your waterfall filter will flow downhill and backinto your skimmer and/or pond which you don't want. This can also represent a decent amount of water in the supply line and filter that will have to be replenished when you turn the pump back on. A power loss can also make this happen, potentially leaving your pond's water level too low on the skimmer intake once it turns back on. A check valve is located shortly after the pump discharge and before a disconnect union or rubber coupling. It's important that it comes before the disconnect because this allows the water in the line and filter to be drained in the winter if you're not running the system. If the check valve is positioned after the disconnect, the water in the line and filter would still be held by the valve's flap and not empty.

Example #2: The other common application for a check valve is at the beginning of the intake side of an external pump. The check valve should be located below water level in the pond or skimmer/filter from which it is drawing in water. This allows you to initially fill the intake line with water, before the pump is turned on, through the leaf trap or priming pot connected to the pump so the pump can be "primed" and full of water on the intake side. When you close the leaf trap lid and turn the pump on it will begin to circulate water. If you do not fill this line with water many external pumps will not have enough vacuum power to draw the water up and get it to the pump's impeller so it will just run without actually circulating water. Again, if power is lost even for a few minutes water can flow backwards under gravity leaving an air pocket in the intake line. When power resumes the pump will turn on and often not be able to resume waterflow because of this "airlock". This is obviously not good for the motor of the pump or the lack of circulation/aeration of the pond.