Bottom Drain Under Liner to Skimmer
The bottom drain is installed under the liner. Flex PVC pipe carries the water under the liner to the skimmer box. A bulkhead fitting is installed in the skimmer. A PVC male adapter connects the flex PVC to the bulkhead fitting. A valve is placed inside the skimmer box to control flow. When the pump is turned on, water will flow into the skimmer through the skimmer faceplate (surface water) as well as the bottom drain. You can control how much water goes in through the top / bottom inlets with the valve on the bottom drain.
Bottom Drain Above Liner to External Pump Manifold
External Pump Suction Manifold
Use a 2 in. Three-Way Valve as a manifold to join the surface skimmer with the bottom drain. In this diagram we substitute our Large Tadpole for the bottom drain. This arrangement eliminates the need for cutting the liner. Instead, the Tadpole is pulled from the pond for easy cleaning.