How does a pond skimmer box work?

Answer 1

A pond skimmer box, in conjunction with a water pump, skims the surface water, removing a lot of organic material before it becomes waterlogged and sinks. In this way, quite a bit of useless 'bioload' in your pond is prevented, as long as the skimmer is cleaned regularly.

A skimmer box consists of a relatively small (about 1 foot cube, or less), sealed compartment that sits in the top foot or so of the water. It may be permanently anchored at the edge of the pond outside the liner (in which case it requires cutting a hole through the liner that must also be sealed to the skimmer) or it may be a drop-in skimmer that sits in the water and its Plumbing passes over the liner (no cutting or sealing to the liner.) There is a floating 'flapper', called a weir, which constricts the water being skimmed to just the top inch or less and yet can adjust to a varying depth of water (in other words, within several inches, no matter how deep the water in the pond is, due to evaporation or whatever, the weir makes sure only the top inch or less is predominantly is what is being skimmed.)

The skimmer must be connected to a water pump's intake. This creates negative pressure in the skimmer box and draws water from the pond over the weir into the skimmer box, through the pump and out the pump's output. There is usually some kind of strainer in the skimmer box so that the pump does not draw very large bits of debris into the pump, possibly damaging the impeller or pumping mechanism. At least this part of the skimmer is what must be cleaned regularly (as regularly as your pond collects floating debris, once a day is a good place to start) or the pump's intake can become plugged and severely strained. (A water pump's intake should not be restricted, if you want to cut down a pump's flow, cut down the output.)

The water output by the pump, after it has passed through the skimmer, may be further treated (such as by UV, through a pressure bio-filter, etc.) or returned directly to the pond. If the water is further treated - or if the further treatment is the only additional treatment - a skimmer, plus the pump and (bio)filter - can make a very effective and complete filtration system for your pond.

The less expensive, less large (less obtrusive) drop-in skimmers work exactly as well as skimmers as an outside model and offer a lot more flexibility than one that is permanently installed. Permanent ones often have additional filtering built into the skimmer box, making them very large but then everything - skimmer and filter, sometimes also the pump - is in one box, the "skimmer." In some cases, depending on your landscaping, etc., drop-in ones are more noticeable than permanent models, but with some creativity they can be hidden or camouflaged easily and you will save a bunch of money and a lot of frustration if you need/want to reconfigure the skimmer's position or make other plumbing design changes.

Have fun with your pond!