Skimmers are designed to remove debris floating on the pond surface. The skimmer is only effective as long as the debris is still floating. All skimmers have a debris collection system inside that will have to be emptied occassionally. The frequency of which will depend upon the amount of floating debris in the pond. It is critical that the debris be removed from the filter basket, mat or net when necessary so that water flow through the skimmer (and into the pump) is not impeded.
Types of Pond Skimmers
There are two basic types of skimmers. One is an out-of-pond unit. These units are made in various sizes that are suitable for a wide variety of ponds. They are best installed during initial installation of the pond liner. They are large units that are placed with the skimmer mouth at the surface of the pond. The pond liner is secured to the face of the skimmer and a hole is cut in the liner so water can enter the skimmer. Due to the fact they are attached to the liner, this type of skimmer is best installed into new pond construction. They have the advantage of being located outside of the pond at the pond edge. Many come with a decorative cover or can be covered so that they blend into the surrounding landscape. The fact that they are outside of the pond makes maintenance relatively easy. This type of skimmer usually has a submersible pump placed inside of it. The pump is protected from clogging by the debris collection system. It is critical that the debris be removed from the skimmer so that it does not impede water flow into the pump. The fact that the pump is not submersed in the pond makes access to the pump relatively easy. It is best to place the skimmer at the pond edge in a location where it is away from where the water from the pump will be re-entering the pond. The idea is to set up a circulation pattern between the skimmer intake and the pump discharge, be it an upflow filter, waterfall, stream, etc.
The second type of skimmer is an in-pond unit. They tend to be made for smaller ponds and you will have to find a way to empty the debris basket which may require you to wade into the pond quite frequently. This type of skimmer usually has a pump incorporated into it or is hooked with a hose to the intake of a suitable pump. It is critical that the debris collection system be maintained so that the flow of water into the pump is not restricted. This type of skimmer can be installed at any time.
Pond Skimmer Selection
Skimmers are sized for both the surface area of the pond they will be skimming and for maximum flow rate through the skimmer. When selecting a skimmer, you will have to consider the requirements of the other equipment within the pond (i.e. filters) or the requirements of your waterfall. You have to choose the skimmer based upon the larger of these criteria.
Your pond has a surface area of 130 square feet. You could use an Aquascape Microskim skimmer. It is rated for up to 150 square feet and requires a pump with a flow rate between 500-2000 GPH.
Your pond has a surface area of 130 square feet and you have a 20 inch wide and 4 ft. tall waterfall across the pond that will require a flow rate of at least 3,000 GPH at the top of the waterfall. Depending upon the pump chosen, you are looking at a pump with a maximum flow rate of close to 4,000 GPH. You will need a skimmer like the Savio Livingponds Skimmerfilter that can handle this larger flow rate even though it is oversized for the surface area of your pond.
It will also depend upon if you are installing the filter into an existing pond or if the skimmer is being installed into a pond while under construction. An in-pond skimmer is always the easiest choice for an existing pond.
The final selection criteria is if you want a skimmer with a UVC. At this time, only the Savio Livingponds Skimmerfilters have an optional UVC component that can be added to them. This is a good choice if you are thinking of having a UVC in your pond and the accessibilty to an electrical outlet is a consideration (power is already near the skimmer because you need to supply the pump). In some cases, this may be an easier choice than purchasing a filter with a UVC, adding a UVC to an existing filter or adding a UVC inline between the skimmer and filter.