Fountain Pumps: How to Choose the Right One

Using readily available materials, you can easily make your own water fountain for your house or garden.

The pump is at the heart of every fountain. Until recently all pumps were of the “direct-drive” style. Lately, however, very small tabletop fountains have become possible through the introduction of the magnet-drive motor. Solar powered, low-voltage fountain pumps are now available.

The pump often turns out to be the most expensive component of the fountain, ranging in cost from $30 to $100.

For each inch (25 cm) of stream width at the top of the fountain piece, choose a pump that will deliver 100 gallons (380 l) per hour (GPH) at the height of the overlow point (known in the trade as “the head.”

Your pump supplier can tell you how many gallons per hour (GPH) each model delivers at different heights above the pond’s surface (feet of head).

Select a pump that delivers at least 500 GPH (1,900 l per hour) at 3 feet (90 cm) of head.

DIRECT-DRIVE PUMPS
The motor is encased in an oil-filled waterproof shell with seals around the cord and impeller shaft. The usual size and output power of direct-drive pumps made small indoor or garden fountains difficult to construct.

MAGNET-DRIVEN MOTORS – SMALL TABLETOP FOUNTAIN
The impeller is attached to a magnet that twirls in a chamber outside the epoxy-sealed pump housing. The chief advantage of this design is that the wiring is sealed off from the moving parts. Water and electricity are kept apart by a solid plastic wall. Far less bulky than direct drive models, mag-drive results in smaller pumps. It is significant, too, that epoxy, a solid and inert material, cannot lead from the housing — as can the oil from a direct-drive pump.

Most small plastic pumps are of the mag-drive type. These pumps are less powerful than the direct-drive pumps (sometimes an advantage in small fountains) but more prone to jamming. Not only is there a whirling impeller to jam whenever a bit of leaf or twig finds its way past the intake screen, but there is also a cylindrical magnet spinning in a well where silt-laden water is circulating. Even the crumbs of calcium carbonate formed by the evaporation of hard water can jam the magnet. This sensitivity to jamming may limit the use of mag-drive pumps to cleaner, indoor applications.

SOLAR POWER
Solar-powered appliances, which include low-voltage fountain pumps attached to a small solar panel, are becoming easier to find. Although these pumps are many times more expensive than conventional models, you will realize savings by not needing an outdoor electric outlet. Such a pump can also pay off if your fountain is a considerable distance from your power supply. If you live where the sun shines most of the time, this may be a practical alternative.

SIZE, INTAKE, AND OUTFLOW
* Choosing a pump for a small tabletop fountain involves different concerns than for an outdoor water feature. The most important one is output. Generally, your challenge will be to find a pump that will deliver a small-enough flow of water, since splashing is destructive to surrounding furniture.

Consider also the physical size and shape of the pump housing. Ideally, this will be completely concealed when your fountain is assembled. When choosing your pump, imagine it in the fountain and you will construct. Is the outflow on the top of the pump or on the side? Will this matter in your fountain? Is the water intake on the bottom or on the side? If you need to orient the pump so that the intake is on the pump’s side, will the depth of the water reservoir allow this intake surface to be completely covered? (This is necessary for the pump to draw water.)

Most tiny pumps come with suction-cup feet to help hold them in place. Because the pumps weigh very little and are attached to relatively stiff tubing and electric cords, this can be an asset. Often, however, the design of your fountain will dictate a different orientation than the feet suggestion.