Pond fountain or aerator: how to choose

Most pond owners start with the same picture: a white plume in the middle of the water. Some of them need that fountain. Others have a deep pond, and the plume will never reach the water that is short of oxygen.

The two tools do different jobs. University extension services have measured what moving water does for a pond and what it does not, and their findings settle most of the choice.

Fish breathe oxygen that is dissolved in the water. Pond scientists call it DO and measure it in milligrams per litre. Warm water holds less of it than cold water, so the tight months are July and August.

Oxygen gets into a pond from the air, from plants and algae during daylight, and from streams. At night the plants stop making it and everything in the pond keeps using it. The low point comes just before sunrise.

A machine adds to that natural supply. It does not replace it, and a healthy pond may not need one at all. Oklahoma State University Extension puts it in plain words.

So the first question is not which machine. It is what you want from the water: a spray to look at, a safer summer for the fish, less muck on the bottom, or all three. The answer points to a fountain, to an aerator, or to both.

A floating fountain is a pump under a float. It pulls water from just below the surface and throws it into the air. The drops pick up oxygen on the way down and the splash stirs the top layer. Our F2 moves 15,000 gallons an hour this way.

That is the honest limit of a fountain. Penn State Extension describes it without flattery, and we would sooner you read it here than find it out in August.

For a shallow pond, the surface layer is most of the pond. A fountain there does real work, and it is the only tool of the two that you can enjoy from the porch. For a pond 15 or 20 feet deep, the spray is decoration on top of water it does not touch.

A bottom aerator keeps its machine on shore. A compressor pushes air down a weighted hose to a diffuser on the pond bed, and the diffuser breaks the air into small bubbles. Our A3 runs 2 diffusers from one compressor. The rising bubbles drag bottom water up with them, and that slow lift turns the whole pond over.

There is no plume. From the bank you see a patch of boiling water about the size of a kitchen table. People who buy an aerator for looks are disappointed, and people who buy it for the fish are not.

A floating fountain and a bottom aerator differ on six counts. The one that decides is when each is the better choice.

Many ponds end up with both. The aerator runs for the water and the fountain runs for the evening. If you can afford only one and the pond is deeper than a tall man can stand in, extension advice leans toward the diffuser.

Measure before you order. Tie a weight to a cord, mark the cord every foot, and drop it from a boat or the end of a dock in 5 or 6 places. Write down the deepest reading and the reading where the fountain would float.

Size matters as well, and no table on a web page can size a pond for you. The extension service puts it bluntly, and we agree with it: ask someone who will look at your pond.

These are the machines we make for ponds, with the figures from their product details and the current prices. Ratings are what buyers have given them so far.

The F2 and the F3 share one pump: 1 HP, 750 W, 15,000 gallons an hour, on 100 ft of cord. The difference is the float and the lights. The F2 rides a blue square float and takes a separate light ring. The F3 rides a black octagon and can carry 4 lights on the float itself.

A 1 HP pump draws about 750 watts. Run it for an hour and it uses 0.75 kilowatt-hours. Your bill charges by the kilowatt-hour, so the arithmetic is short: hours a day, times 0.75, times your rate.

Take the monthly figure and multiply it by the price per kilowatt-hour on your own bill. Rates differ by state and by season, so the dollar figure is yours to work out.

Oklahoma State gives a way to cut that bill without giving up the benefit. It applies to surface units such as fountains.

Each of our fountains comes with a timer, and the same timer is sold alone as the Outdoor Programmable Timer Switch. It holds 20 on and off programs on a 7-day cycle. A schedule also rests the motor. The A3 kit includes a timer for the same reason.

• Night aeration: on at 8 in the evening, off at 7 in the morning.
• Show hours: on from late afternoon until bedtime, when someone is there to look.
• Split run: 2 hours on, 1 hour off, around the clock in a heat wave.

Buyers of the timer tell us two things. They like that it survives rain under its clear cover. They do not like the small terminals, which are tight to wire, and the clock shows 24-hour time only.

A fountain is a one-person job with a small boat or a pair of waders. Lay everything out on the bank first and check the parts against the manual.

Our Fountain Pump Filter Bags go over the pump before it gets wet. A mesh bag keeps leaves and string algae out of the intake. It also needs rinsing, because a clogged bag starves the pump. Check it after the first week and then monthly.

The same 15,000 gallons can go up as a narrow column or out as a wide umbrella. That is the nozzle's doing. A fountain ships with 3 nozzles, and our Fountain Nozzles N1, N2 and N3 add more shapes.

A tall pattern loses more water to wind. On an exposed pond, a low wide pattern keeps the water in the pond and the float where you put it. One buyer found that our nozzle did not fit another make of pump, so check the collar size first.

Light does nothing for the fish. It is there for you, and it is the reason many people buy a fountain in the first place. We make it two ways.

The F3 lights switch with the pump, so they also burn through the day unless the timer turns the whole fountain off. The F0 ring has its own cord and its own remote. A few buyers of each report trouble with the remote, and the first fix is a fresh battery and a shorter distance.

The A3 Pond Aerator arrives as a compressor, 2 rolls of sinking hose, 2 diffusers, a timer and a bag of fittings. Plan the layout on paper before you unroll anything.

The last step is not fussiness. A pond that has sat in layers all summer holds water at the bottom with almost no oxygen in it. Stir that up in one go and you spread the bad water through the good.

We read our own reviews on this product closely. Several buyers had a hose burst near the compressor in the first days. In each account the ordinary hose was joined straight to the hot outlet. A spare roll of Self-Sinking Aerator Hose is sold separately for longer runs.

In a cold state, ice changes the job. A frozen, snow-covered pond gets no oxygen from the air and little from plants. An aerator that keeps a hole open lets gas pass both ways.

Open water is also thin ice. If people skate or fish on your pond, mark the open area and keep the diffuser in the shallows for the winter. A floating fountain is a warm-season tool. Take it out before a hard freeze and store the pump indoors.

A fountain puts 110 volts on a cord that ends in a pond. Treat that with respect. The outlet should have ground-fault protection, and the cord should be whole from plug to pump.

The same rule holds for a pond with a powered fountain in it. Unplug the fountain before anyone wades in to move it, clear weeds or change a nozzle. The 10 seconds at the outlet are the cheapest safety step there is.

Praise for the fountains is about the size of the spray and how fast they go in. The complaints are about pumps or lights that stopped in the first season, and one buyer reports rust on a pump after a month.

Keep the order record for any pump. Our fountains carry a 3-year warranty, and a claim starts from that record.