Pond surface skimmers explained

Surface skimmers are a very worthwhile addition to any pond filtration system. Whereas a typical pond pump only removes debris that sinks down to the bottom, a surface skimmer will remove any surface debris that won’t sink, aiding water quality, and improving viewing.

Surface skimmed water is healthier because any oils or residues are removed, meaning better gaseous exchange. Pollen, petals, dust and leaves are removed too, meaning they exit the system before they break down, and add to the pond’s biological load. 

There are three types of surface skimmer available.

The first is a box which you actually build into the side of a block built pond. These are popular with koi keepers and they work by being fixed into the wall, and water overflowing into them. They have no prefilter, and will need to be connected to rigid pipework, then connected to a mechanical filter.

Retro fitting is tricky, and these are best pre-planned before the pond is built, and as part of a comprehensive koi filtration system.

Next are both in-pond surface skimmers, meaning that they can be added or removed at any time, and actually sit in the pond, in the water. One needs to be powered by a separate pond pump (not supplied) and ideally a pond pump with two inlets like the Oase AquaMax Eco Premium.

This then means that one pump can pull debris from the bottom like it normally would, while at the same time removing floating debris from the surface. It literally is the best of both worlds if wanting maximum filtration capacity from just one pump.

Then there is the self contained surface skimmer, like the Swell Pond Skimmer 3000. Self contained pond skimmers have many advantages including low cost, suitability for almost any sized pond (including small ones) and they come with their own built-in pump, so can be used entirely on their own and won’t effect or necessitate an existing pond filtration system. 

The Swell Pond Skimmer 3000 is also free floating, so it can operate in virtually any depth of water, as long as it is deep enough for the unit to float without touching the bottom.

How it works

UK law states that pond appliances are not allowed to be sold with pre-fitted plugs, so you’ll need to wire the skimmer into an RCD plug, or a certified outdoor safe electrical switch box. Once you’ve done that familiarize yourself with the product.

The pump sits upside down in the bottom case and pond water is drawn in over the adjust ring before floating waste is trapped in the collection cup. The unit free-floats by way of three floats, which must be attached before the unit is placed into the pond. 

BEFORE OPERATION

Ensure that the pump and bottom case on the unit are fully submerged and fully tilted before turning the unit on. Without doing this air will be trapped in the base of the unit, forcing it to float higher in the water column, and it won’t skim properly. 

So submerge, tilt 90 degrees under the water to release air from the base, turn back the right way up, and switch on. The skimming effect will be immediate, and leaves will be drawn slowly towards the skimmer before oveflowing into the collection cup. 

A tether string is supplied, which can be tied around one of the floats, so that the unit can be retrieved easily from the middle of the pond once full of leaves.  

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Jeremy Gay is an author and freelance aquatic specialist. A former editor of Practical Fishkeeping magazine, he offers a wealth of experience on all things aquarium and pond.


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