How do Skimmers work?

by: Demi Fortuna

As mentioned previously, we can categorize Filtration as Mechanical, the separation of particles by settling, screening or trapping them in filter media, or Biological, the removal of unwanted substances in the water by living organisms. Some filters, like Skimmers, are only mechanical, others (less common types we won't be getting into) are purely biological; Submersible Filters, Pressurized Filters, External Filters and even Bogs do both.

Pond Skimmers are Prefilters that work almost entirely mechanically to remove physical debris from the surface of the pond before it can sink to the bottom, saving you lots of time and trouble later. There are many ways to remove debris, and there's probably a Skimmer for every way, but most are set up similarly. A door is equipped with a floating weir that assures that mostly surface water is drawn into a net or basket that captures large debris like floating leaves. The water then passes through a set of brushes, a mat or a pad that traps algae, dust and pollen, then into a pump chamber where it is pumped out by a pump, typically up to a waterfall or filter. A second, equally important function is to house and protect the pump, constantly providing clean water, keeping the intake from clogging and sediments from wearing down the impeller. With the pump so close at hand and easily accessible, folks might even find it easier to maintain it regularly (or at least manufacturers hope so). Problems arise when some Skimmers aren't cleaned regularly, or water levels drop below the mouth of the Skimmer – if the flow of water to the pump stops, the pump can overheat and eventually burn out. Well-designed Skimmers allow water to get to the pump even when neglected, like the brushes in Atlantic Skimmers that push aside when fully loaded, never starving the pump of water.