Pond Skimmers for the Koi Pond Or Koi Water Garden

Pond skimmers are a vital part of any koi pond or watergarden and is an important choice when considering construction of an outdoor pond. Like all products there are many brands and sizes of pond skimmers to choose from. Factors that determine the size, number and brand include the size and shape of the pond, how many fish, and how many leaves end up in the pond. The main purpose of the pond skimmer is to skim debris and amino acids off the surface of the water before they have a chance to break down and foul the water. The skimming action is created by the face plate or weir which has a floating door. The reason the door floats is to insure that most of the water entering the skimmer is pulled from the surface of the water at different water levels. From there the water goes through a leaf net or basket to catch large debris and can be emptied with ease. Then the water goes through a mechanical filter of either course filter pad or filter brushes. This acts as a mechanical filter and also provides biological filtration. The next phase the water goes through is the pump chamber that usually houses the main pump or pumps for the pond where it is pumped to the other end of the pond, a waterfall or a stream that flows into the pond. It is important that the skimmer and water return are on opposite sides of the pond to insure good waterflow through out the pond surface area with no stagnant areas. Stagnant areas breed mosquitoes and the pond shape may require more than one return or more than one skimmer.

Water Flow and Pump Size

Before choosing a pond skimmer it is important to know how much water movement is required for the koi pond or koi pond watergarden. Ideally the entire volume of the pond water needs to be turned over at least once every two hours. For koi only ponds this rate should be once every 1 - 1.5 times per hour. For example a 5,000 gallon pond would require 2,500 gallons per hour flow rate. To calculate the volume of water multiply the average length times the average width times the average depth to get the cubic feet of water. Multiply the cubic feet times 7.5 to get the volume in gallons. For example a pond 12 feet long, 8 feet wide and 2.5 feet deep would have 240 cubic feet of water (12 x 8 x 2.5 = 240). 240 x 7.5 = 1,800 gallons of water. This would require at least 900 gallons per hour of water movement. The next thing to consider is how high the water has to be pumped. This is called head pressure, which most high quality pumps will list in their specifications. For instance, a 1,200 gph pump may only pump 900 gph at 3 ft. of head pressure. The size of pipe will also make a difference in the pump flow rate. For best flow rates the pipe inside diameter should be 1/2 inch larger than the pump outlet size. If a pump has 1 1/2 inch outlet the pipe inside diameter should be 2 inches for best flow rates. The piping will still cause some restriction and 100 gph for every 10 feet of piping should be added to the pump size. Now lets put it all together. The pond is 12 x 8 x 2.5 and has a waterfall that is 3 feet above the water line and the total length of pipe used is 20 feet. 12' x 8' x 2.5' = 240 cubic feet. 240 x 7.5 = 1,800 gallons. 1,800 / 2 = 900 gph. 900 + 200 = 1,100. The pump size needs to be at least 1,100 gph @ 3' head pressure. It is important to realize that koi can grow very fast and it is best to account for that when determining waterflow and filtration requirements.

Once the waterflow requirements have been determined the size of skimmer can be determined. Most skimmers are rated in size by the maximum and minimum gallons per hour of water that they can handle. It is best to choose a skimmer that has a higher maximum and lower minimum flow rate than the pump used.

Top Brands and Features of Pond Skimmers

The top brands of pond skimmers on the market today are Atlantic, EasyPro, and Savio. Each has accessories that can be incorporated in the skimmer like UV sterilizers and auto fill valves. Atlantic has more sizes available than the other manufactures. The Atlantic PS4000 and PS4500 utilize a leaf basket and filter with flow rates from 500 - 4000 GPH. The Atlantic PS4600, PS4900, PS7000, and PS9500 incorporate a leaf net and filter brushes with flow rates from 3,000 - 9,000 GPH. The filter brushes can be replaced with a filter media pad as a matter of preference. EasyPro offers three sizes of pond skimmers and use a leaf net and filter brushes with a separate pump chamber for easy maintenance. They have the largest leaf net of their competitors which is a must if there are trees close to the pond. They range in sizes of 3,000 - 15,000 GPH. EasyPro also has an external pump skimmer for use with an external pump and also incorporates a fitting for using a bottom drain. Multiple external pump skimmers can be plumbed to one pump, ideal for odd shaped ponds where one skimmer is not enough. Savio has the Compact SkimmerFilter and the SkimmerFilter. Different size faceplates are available for each skimmer for different flow rates from 700 - 8,500 GPH. They use a leaf basket and filter media pad. Options include the UVinex which is a UV sterilizer that mounts in the skimmer and different sizes are available. If more than one pump is used the Atlantic Big Bahama and the EasyPro Large skimmers are the best. EasyPro's new Axiom Skimmers with a front-to-back design have plenty of room for pumps and bilogical filtration.  For features like an internal UV sterilizer or auto fill valve the Savio Skimmer filter is the best. For small pond applications the Savio Compact Skimmerfilter is the best unless you are on a limited budget and then the Atlantic Skimmer fits the bill.

Choosing the right pond skimmer and pond pump will make a big differnece in the success of creating and maintaining a beautiful koi pond or koi watergarden with healthy fish. It is much better to spend the money up front and not have to upgrade or replace these two vital parts of the water pond later. Buying a cheaper pond skimmer or pond pump does not always save money.