The Importance of a Pond Skimmer


BY: Gary Wittstock

Co-Authored with Ed Beaulieu

The year was 1988; we were in the 6th year of our hobby, we had a love/hate relationship with our pond as most pond owners did during the early years of the hobby.

The allure of a crystal clear pond was nothing short of a dream as it was only achieved the day after it was filled with fresh water.

As the season progressed the fish slowly disappeared under a cloudy layer of surface scum and green water not to be seen until the next year’s pond clean out. And what a mess that always was!

Our quest had begun!

How could we lower our maintenance and improve overall water quality?

We started experimenting and researching everything we could but this was pre-Internet, we actually had to go to the library to find information on our new found love affair with aquatic ecosystems…

Garys Blog - pond pumps hard to access
Pond pumps are difficult to access if not using a skimmer.

Some of our challenges with our first concrete soup-bowl pond were:

  • Clogged pumps that sat at the bottom of our pond
  • The challenge of hiding the pump hose from the pond to the falls
  • The large quantity of debris that accumulated each year on the bottom of the pond (2-3″ of pond-scum)

Garys Blog - hard way to skim pond
The HARD WAY to skim clean a pond.

Garys Blog - clogged pump
Clogged pump from in pond use.

Shazam! What do we find but a Family Handyman article on skimmers for ponds. Jackpot. It was a garbage can fitted with a pool skimmer. Finally a way to catch debris before it sank to the pond bottom, hide the pump outside the pond AND… get the pump tubing outside the pond without trying in vain to hide the pump discharge pipe. That pipe could now be buried outside the pond as it headed over to the water fall because the pump itself could be installed outside the pond.

Garys Blog - garbage can skimmer
Garbage can skimmer

If there was just one filter I could choose when installing a pond, hands-down it would be a skimmer. Here’s why: A pump is necessary to create circulation for filtration and to create a waterfall (one of our favorite pond features!). And as long as you’re going to have a pump why not move that pump outside the pond so it can move surface water to create a skimming action and be easily accessed for service. Also, and this is HUGE. ALL PONDS ACT LIKE DIRT TRAPS. As the winds blow the currents carry all manner of dust and debris that are captured by the surface of the water. All this dust and debris like leaves and seeds in particular, get trapped by the water and soon sink to the bottom of the pond. Once there they will foul the water, turn into “pond scum” and are very difficult to remove without draining the pond. Even bottom drains which do help keep deep ponds cleaner cannot clean the entire bottom of a pond without jets, aeration and other complex and costly additions. But by simply placing and hiding a pump outside the pond the simple power of that pump in a well-designed skimmer filter will PREVENT most pond debris from ever sinking into the pond by skimming the surface while this debris is still floating on the pond’s surface. Skimmers are essential to keep any body of water as clean as possible and there’s no better filter for reducing pond maintenance and keeping the water safe for your fish!

Garys Blog - original skimmer design
Original Skimmer design.

I’ve heard and understand arguments that moving the pump outside the pond impairs full top-to-bottom pond circulation. On shallow ponds like water gardens that are two feet or less deep this is not an issue. The skimmer alone will create enough current in the pond to ensure full circulation. On deeper ponds that are 4 or 5 feet deep jets or bottom drains can be added to ensure optimal circulation.

Pond Circulation - Skimmer Vs Bottom
Placing the pump in the deepest area draws currents from the waterfall, but not the far end of the pond. Locating a skimmer on the opposite end from the waterfall ensures full pond circulation.

Also locating the skimmer on the perimeter will automatically increase the overall circulation of the pond versus having the pump located on the bottom in the deepest point. Ideally place the skimmer on the opposite side of the pond from the waterfall for optimum circulation.

A skimmer acts as a safety system for your pond and fish, if any type of water loss or leak occurs in the piping system, waterfall or stream; the skimmer will only allow the water loss to occur in the top 6″ of the pond or basically to the bottom of the skimmer opening. When the pond water level reaches that point no more water will enter the skimmer so the pond will stop draining! When the pump or bottom drain are located on the bottom of the pond they will completely drain the pond of water during a leak leaving the fish high and dry! I’ve heard many a horror story of just that happening and it’s truly tragic.

The skimmer is also the perfect measuring device; the skimmer opening will show the optimum water level so there’s no guessing what the water level is.

The skimmer is a solid connection point for a waterfill device; the water level can easily be established using the skimmer opening as a measurement. Later in its evolution we added the overflow fitting to deal with excess water.

A skimmer has multiple barriers in place to keep critters from getting to the pump compared to putting a pump directly in the pond.

When we tore out portions of our classroom concrete pond to fix the leaking basin and ugly pond edges, we also added a new garbage can skimmer complete with its own set of wheels. We followed the directions from the article and added a net bag that we purchased from a dry cleaner. It was a laundry bag that was quite strong and suitable for catching the debris our new skimmer would collect from the pond’s surface. We purchased a swimming pool skimmer with a 6″ opening and built-in plastic weir that floats on the surface of the pond. This is a very valuable part of the skimmer design as the floating weir ensures optimal surface flow so most of the pond debris gets pulled into the skimmer net or filter pads before it can sink. We modified the standard swim pool skimmer by cutting off the circular collection basket behind the weir. In swimming pools this is where the external pump is attached. We much prefer to use submersible pumps so by cutting off the collection basket we could then simply attach the weir and holder to the face of the garbage can, inserting a submersible pump into the garbage can under and behind the debris and filter pad(s).

Our new cobbled-together skimmer worked great but the pump, a Little Giant #6 (3,000 gph), had a protective screen to prevent debris from damaging the impeller. That screen clogged every week but we still loved this skimmer. After all, the pump was now OUTSIDE the pond so lifting the pump out of the skimmer was pretty easy. I even installed a flexible radiator hose on the pump discharge and tied a rope to the pump. That way we could just pull up on the pump rope and access the pump & screen for cleaning without taking the plumbing apart or having to wade into the pond. What a maintenance boon!

Garys Blog - easier pump access with skimmers
Pumps could now be accessed easily.

Even though the skimmer worked just as planned we still felt the need to add more filtration. The skimmer was really a mechanical skimmer removing most floating debris before it would sink where it could foul the pond. I thought if we added a filter pad or pads to the skimmer we’d have a large surface area biological filter and that would help clarify the water and process the fish waste safely.

Garys Blog - skimmer cleaning pond of maple seeds
Skimmer cleaning pond of maple seeds 

Well we soon found out that since our pond was 1,000 gallons the biological capabilities of this skimmer were still a little too small. (Next week we’ll review the evolution of our BioFalls). However the filter pads did add a huge benefit; the small debris that used to slip through the debris net was caught more effectively by the filter pads. So now the pump lasted much longer before the pump screen needed cleaning.

Also, when a skimmer is used in conjunction with a Biofalls® or any biofilter it increases the efficiency of the filter:

A skimmer’s pre-filtration will protect the biofilter from collecting excess organic debris so it will effectively breakdown fish waste. The biggest problem for biofilters is clogging with too much waste which does not breakdown efficiently. A skimmer also uses water from the surface of the pond which has the highest available dissolved oxygen content. High dissolved oxygen is very important for efficient bacterial utilization of nitrogen compounds(fish waste).

We installed close to 100 ponds with this crude garbage-can skimmer but only one customer ever complained about this kind of “home-made” filter. And when he did I visited with him and told him if he could find a better skimmer we’d install it No Charge. We never heard from him again! By the time we had installed this many skimmers our business had grown to the point that we could afford tooling to build our very own custom Aquascape skimmer. We turned to a plastic manufacturing technique called “rotomolding” as the tooling was relatively inexpensive while the quality of the product was superb. A plastic charge of powdered product was introduced into a mold and the mold was heated and rotated. When the plastic melted it spread out inside the tooling to form the skimmer box. And it concentrated most at all the corners giving us exactly the strength we were seeking. No longer did we need to encase our skimmers in plywood like we did for the garbage can model – LOL. We tested this rotomolded housing by filling it up to the skimmer opening with water and letting it freeze solid. It passed with flying colors!

Garys Blog - winter freeze test
Winter freeze test

Here’s one of our original drawings to show our customers how the Aquascape skimmer was designed:

Garys Blog - original skimmer diagram
Original Skimmer diagram

At Aquascape we’re proud to say this same plastics company we started with in 1994 is in Wisconsin – so we’re able to use an American company for most of our molded plastic products to this day! And year after year we still run into fully functional garbage-can skimmers when we upgrade/enlarge ponds for our past customers – some of these skimmers have been running over 20 years and they still don’t miss a beat!

Notice the Seal of Approval from the National Pond Society? Sadly that organization and their PondScapes publication is not around anymore but we joined up with them in 1994 to help further the causes of our industry when it was just getting off the ground. We’ll do another blog on that group one of these days.

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Author: Bobby Kenyon
Bobby Kenyon is the Creative Solutions Guru for C.E. Pontz Sons who has over a decade plus experience in the Landscape & Water Garden industry . He enjoys long walks on the beach and grocery shopping but has a strong dislike for regular cake and off brand paper towels

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