What is a pond skimmer?
If you’ve ever been to a swimming pool you’ve probably seen a surface skimmer. Water is drawn into the filter system through one or more of these filter devices. Surface skimmers pull water into the filter system from the water surface.
Surface skimming removes bugs, oils, foam and other floating objects from the pool water, keeping it crystal clear. Pond surface skimmers work much the same way but are designed for use in fish ponds and water gardens.
Chances are your pond does not have a surface slick of sun tan lotion, hair care products and corn chips. But our ponds do collect floating leaves, natural oils from algae and surface foam.
Why do I need a pond skimmer?
Fish foods contain essential fatty acids, protein and other ingredients that cause an oily surface film, especially in heavily-fed koi ponds. Plants and algae also release natural oils that float on the surface. Pollen from flowers and trees will collect on the water too. Tree leaves, grass clippings and other plant material always seem to find their way into the pond water.
All of this organic material will create unsightly foam and murky water. Even fish slime can cause clumping of organic debris that prevents the water from looking sparkling clear.
Regular submerged and external pond filters cannot pull surface films and floating debris from the water surface.
A pond skimmer will skim off the surface layer of the water. Skimmers also act as a pre-filter, capturing floating solids before they enter the pond pump and biological filter. Skimming protects your pump from getting clogged or jammed up.
A pond skimmer keeps large particulates from gunking up your biological filter too. A skimmer reduces manual skimming with a skim net, cutting time spent on maintenance. We often get busy and don’t have time to skim the pond by hand. Eventually the debris settles to the bottom of the pond and begins to decay.
How does a pond skimmer work?
A pond skimmer works by dragging water into the skimmer box by means of a submersible water pump inside the pond.
Skimmers use a “weir” or floating door that pivots at the bottom with the top edge positioned just below water surface. The door floats so that most of the water entering the skimmer is pulled from the surface no matter what the water level is.
The incoming water is forced over the top edge, creating a high level of tension across the pond. The closer the weir edge is to the surface, the more surface tension and better skimming action. As water passes through the unit large debris is trapped in a mesh net or fine basket before it is pumped back into the pond.
Pond skimmers need to be positioned level with the water surface so the surface of the water can flow into the box. The skimmer catches large debris like leaves and collects them in its own filter basket. This prevents the debris from clogging the hose and water pump.
Some skimmers have a removable lid to hide the basket. The water pump sends water to the back into the pond or into an external pond filter for further purification.
How to select a pond skimmer
It’s important to know how much water movement is required for your koi pond or water garden.
At a minimum, the entire volume of the pond should to be circulated at least once every 1-2 hours. Heavily stocked koi ponds typically circulate at a rate 1 - 1.5 times per hour.
For example, a 6,000-gallon pond would require 3,000 gallons per hour flow rate. The next consideration is how high the water must be pumped.
This resistance, placed on the water pump, is called head pressure. A pump’s flow rate declines as head pressure increases. High quality pumps will provide a chart showing water height vs flow rate in their specifications. For instance, a 2,000 gph pump may only pump 1,200 gph at four feet of head pressure (4 feet of lift above the water surface). Use head pressure calculations to match the pump to the required flow rate.
The size of pipe and tubing also makes a difference in the flow rate. The pipe or tubing inside diameter (ID) should be ½-inch larger than the pump outlet size. If a pump has 1 ½-inch outlet the pipe inside diameter should be 2 inches for best flow rates.
Once you know the water flow requirements you can compare skimmer specifications. Most skimmers are rated by the maximum and minimum gallons per hour of water that they can handle.
Some pond skimmers require you to cut a hole into the side of the pond (external skimmers). For smaller backyard ponds and water gardens, submersible skimmers are available.
Best Rated Pond Skimmers List
The AquaSkim is a drop-in, internal pond skimmer. No cutting of the pond liner is required.
The skimmer is rated for pumps with a flow rate up to 4200 gallons per hour. The recommended actual flow rate is 1,600 to 3,500 gph.
The floating skimmer can be adjusted to depths between 8-22 inches.
The skimmer’s hose barb accepts tubing from 1-1.5 inches.
The AquaSkim automatically adjusts to a drop in the water level (up to 6 in) due to evaporation and water movement. Floating debris is captured inside the 85-cubic inch strainer basket.
- Economical way to get a pond skimmer.
- Easy to clean.
- No cutting on the liner required.
- Easy to install.
- Not tall enough for deeper ponds.
This in-pond skimmer requires no cutting of the pond liner.
The skimmer must be positioned inside the pond of a plant shelf or other support, at the proper water level.
Water is pumped out the skimmer through a hose by your existing pump.
The TetraPond skimmer has a floating weir door, removable debris basket and mechanical filter pad. This design effectively skims off the surface and traps floating pond debris in the filter pad, making the unit a pond filter and skimmer. A flip-top cover allows easy access for convenient basket removal and maintenance.
Recommended for pumps from 500 GPH to 1,900 gallons per hour. The skimmer uses 1-1/4" tubing.
- Rated for ponds up to 1,000 gallons.
- Well-constructed with thick, quality plastic.
- Easy installation.
- 12" x 11" x 9-3/4" high.
- Input hose is on the back of the skimmer.
- Requires weighing down with gravel or a rock on the lid.
The Laguna pond skimmer is both a skimmer and pond filter. It is designed to be installed outside of the pond, in an excavated hole.
Water enters the skimmer through an opening that you cut in the liner.
The liner material acts as a gasket when attached to the skimmer’s mounting plate.
The Laguna skimmer comes with two pre-drilled 2 ½ - inch pump outlet holes, one on either side of the skimmer box. Inside the skimmer are four large pond filter brushes that capture fine debris and polish the water to crystal clarity.
A water pump with a flow rating of 2,000 and 4,200 gallons per hour is suggested. This skimmer works on koi ponds and water gardens between 1,000 and 4,000 gallons.
- Heavy-duty pond skimmer.
- 17.5 x 24 x 22 inches.
- Uses filter brushes to clear the water.
- Built for larger ponds.
The Aquascape Signature Series 200 Skimmer is an external skimmer that requires a hole to be cut into the side of the pond liner.
The skimmer box is placed at the water level and usually requires placing the skimmer box in a hole, next to the pond.
The Aquascape skimmer works as a surface skimmer and a pond filter.
It is designed for use with water pumps rated up to 3,000 gallons per hour. The skimmer is suitable for koi ponds and water gardens between 3,000 and 6,000 gallons. The removable leaf and debris net makes removal of debris quick and easy.
The rounded shape maximizes the structural design while the durable lid provides protection of the filter components.
The skimmer measures 20" L x 17.5" W x 17.5" H. The Aquascape Signature Series 200 Pond Skimmer is also backed by a limited Lifetime Warranty.
- Lifetime warranty.
- Sturdy construction.
- Comes pre-drilled.
- Leaf net not as sturdy as ridged filter baskets.
- Does not come with filter brushes or filter pads.
All of the pond skimmers in our review work as advertised provided they are installed correctly and use the proper flow-rated water pump. Much of your decision will be matching a skimmer system to your pond’s size.
For simple drop-in installation that requires no cutting, the Oase AquaSkim can’t be beat. The TetraPond skimmer requires some in-pond placement work but it offers skimming and pond filtration in one unit.
If you have a larger pond, you’ll have to cut the liner and install a large-capacity skimmer box. The Laguna Pond Skimmer skims and filters and includes filter brushes, making it a good value.