When installing a skimmer and return line in an above-ground pool, the most important consideration is water circulation. You want the skimmer positioned to effectively pull off surface water to trap floating debris, oils and suntan lotion. You want the return line to send water back to the bottom of the pool to maintain good circulation of the entire pool volume.
The two types of skimmers designed for above-ground pools are the thru-wall skimmer and the floating skimmer, sometimes called a lily pad skimmer. The thru-wall skimmer attaches to the pool wall. Measure a spot on the upper pool wall so the water level will be halfway up the skimmer intake throat. Cut a hole in the pool wall using the template provided with the kit. The inside flange bolts over the inside of the opening and surrounding liner wall to the skimmer body, which mounts on the outside pool wall. Use silicone sealer on both the inside flange and the skimmer body to form a good seal between the two parts. Plumb the line from the skimmer to the pump. You can install a floating skimmer without cutting the liner. Use a flexible hose, such as a pool vacuum hose, to lay over the pool's top edge and attach the floating skimmer to the pump. The skimmer unit is equipped with floats that keep it at the water surface, like a floating lily pad. It pulls surface water in from all sides while the pump is running. For a more permanent installation, attach a thru-wall port (like the thru-wall return described in the next section) and attach a flexible hose from the port to the floating skimmer.
To return the filtered water to the pool, use a thru-wall return fitting or run a flexible line from the pool equipment over the pool wall. The thru-wall return fitting has two parts: the exterior wall fitting and the interior flange. Cut a small hole near the bottom of the pool wall using the template provided with the kit. Put a bead of silicone sealer on the inside surface of each part, line up the exterior wall fitting and the interior flange and screw them together. Attach the return line from the equipment to the outside flange fitting. The simple way to install an "over-the-top" return is to hang enough flexible line (like the pool vacuum hose) over the pool wall so the hose reaches the bottom of the pool and pushes water across the pool bottom.
Skimmer and Return Placement
Place the skimmer and the return on opposite sides of the pool. This way, the water will have a constant flow across the pool, moving and filtering the whole pool volume. It's tempting to install the skimmer and return near each other to minimize plumbing and the run to and from the equipment. However, if you do this, the pool will only circulate and filter the water near the intake and outflow, leaving most of the pool volume unfiltered.