A skimmer is a type of filter that is built into the wall of the main body of the pond. Most skimmers have a basket or bag for catching leaves, filter pads and a chamber for the pump. Since the pump is in the skimmer, it makes maintenance easier than if the pump is just in the bottom of the pond. It also acts as a prefilter so the pump will not clog easily. Some skimmers incorporate a UV clarifier.
These filters are an excellent choice for ponds located near large trees. The basket makes it easy to dump the leaves instead of having to net them out. It also looks better than to have the pump visible on the bottom of the pond. This is considered one of the nicest options for maintaining larger ponds.
Installation requires more effort and experience. Since they are incorporated into the body of the pond, they are difficult to put in after the pond has been installed. It is also important to make sure they are level and the mouth is sealed. This is a common leak point on ponds, especially if they are not installed properly.
First thing to consider is where to put the skimmer. It should be located opposite the waterfall and near an electrical outlet.
Once the dirt is carved for the body of the pond, dig out the area for the skimmer. Just as with a liner installation it is best to dig out the bulk first, then do the precision work. Place the skimmer into the hole to find out where you need to take some extra dirt out to fit it properly. Make sure to remove all loose dirt. If you need to backfill, sand is a much better choice.
After the bulk of the dirt is removed, fit the box into place making sure it is perfectly level. Take your time with this step. If this is not done well the finished product will look uneven. Pay special attention to where you want the water level of the pond. Make sure you are level all the way across. Backfill with sand if there are any gaps from over digging. Don't use dirt. It will settle making the skimmer loose and possibly shift out of place.
After the skimmer is firmly in place and the liner for the pond is also in place it is time to connect the skimmer to the liner. At this step the pond should be filled with water up to just below the bottom of the skimmer. This will insure that the liner won't pull once it is completely filled. Leave a little bit of loose liner under the mouth of the skimmer to accommodate any stretching.
It is recommended to use seam tape or silicone around the edge of the skimmer before you attach the liner. This will add an extra layer of security against leaking. Attach the seam tape to the mouth of the skimmer, then press the liner into place. Run a bead of silicone around the mouth before pressing the faceplate into place.
Place the liner over the hole and place the faceplate over the liner. Screw the faceplate down tight onto the main body.
The very last step after connecting the skimmer is to cut the hole out of the mouth of the skimmer. Don't cut early or the liner may not easily fit the skimmer mouth.