Home / Pond Skimmers. What are they about? And why use one?

Australian pond builders really haven’t been exposed to a good pond skimmer until now. Pond skimmer’s have been used for over a decade in pond building in North America and pretty much any natural pond that is build there these days will have a skimmer box.  A good skimmer will remove the majority of the leaves, dust, pollen and other material that falls into a pond and also provides a good housing for the waterfall pump. Not every pond warrants a skimmer but they are invaluable for over 90% of the natural features built. They can also be easily retrofitted to any sized existing feature where you want the benefits they offer.

There are  in-pond, “floating” skimmers available in Australia but these still rely on a pump at the bottom of your pond and are also generally the most visible thing in there which sort of destroy’s the whole visual appeal of the feature. A good skimmer is positioned on the  outside of the pond making it easily reached and hiding it away.

So what ? you may ask!  Lets have a closer look.

Leaves and debris in my pond? I can just net them out.  Yes you can if your out there diligently every day, especially during leaf fall in autumn in the south or the end of the dry season in the north, but on the days you dont they sink to the bottom. Who wants to be constantly scooping out your pond anyway?  As the organic materials break down they release nutrients and become the sludge and a great algae producing area on the bottom of your pond. This nutrient load is used by aquatic plants but it also promotes algae. The more sludge, the more nutrients and  the more water quality issues you will have. With out a skimmer your pump is also down there with the sludge and algae which begin to block the intake to your pump. Anyone with  this type of set up will know the frustration of having to clean off your pump intake, sometimes daily. Pumps also burn out more frequently.

The skimmer  improves water quality by removing the pollen, dust and small debris floating on the surface which can make a pond look cloudy or oily.

A clean out basket or bag similar to that  found in a swimming pool makes it easy to clean.

So..a skimmer

  1. Removes the majority of the leaves and detritus before they sink to the bottom, reducing the nutrient load in the pond
  2. Keeps the surface clear so you can see down into the pond
  3. Protects the pump, no more blocked intakes
  4. Easy maintenance, just lift the lid and empty the basket or bag. This is great for less agile people as there is no more reaching into the pond to clean off the pump
  5. No more pipes or plumbing in the bottom of the pond. Whats all that about anyway?
  6. If your piping or waterfall leak then the pond will not fully drain. This protects your fish from full pump out because the pump is not at the deepest point

Now if you go to your local pond shop and ask about a skimmer you will probably get a blank look and some of the following reasons why skimmers are not good.  Keep in mind that the majority of the sales people will have neither seen, used or installed a good side mounted skimmer unit. To be fair the only skimmer exposure would have been the tube type surface units that sit in the pond.

You will hear:

  • That a  pond with a skimmer does not  filter right because it only “skims” the top layer of water and the deeper parts are not moved by the pump to the filter
  • That a “thermocline”  in the pond stops the correct filtration and you get different oxygen levels forming
  • If the pump isn’t at the bottom of the pond then how is the sludge pumped to the filter?

OK. A properly designed pond has the skimmer at the far end opposite the waterfall or creek entry. This means that you will have good flow through the pond and the water that has been oxygenated by the waterfall or creek then mixes with the total water volume – aeration.

A pond is not static, water is constantly rotating due to the influence of heat (sunlight) and cold so it is constantly mixing.

There is also the basic  principle of diffusion, that a high concentration , in this case oxygen, will naturally move to areas of low concentration to find equilibrium. Sounds complicated but its not, we all learned this in school. You will get a cooler body of water at the bottom of the pond but this is a good thing as different aquatic organisms and plants have their temperature preferences. It promotes a healthy pond ecology.

Plants, zooplankton and algae  also release oxygen into the water making it even more important to have a variety of  depths, temperatures  and habitats available for a good varied mix of life that supports an overall  healthy pond ecology.

Sludge build up  will be discussed in another topic. Enough now to say that in a properly built and stocked pond its not a problem.

Now you do have to clean the skimmer out –  two or three times a week in the high leaf fall season of the year, once or twice a month the rest of the year.  But this is a lot easier then netting out the leaves constantly and takes about  two minutes to do.

More later..

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