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Water Feature Knowledge Base - Need to Know (NTK)


If you try to start your pump and continue to lose prime, it may be an air leak. See TROUBLE SHOOTING If this is not a problem, you may have an air lock in the intake pipe from the pond to the pump. This means the pipe goes up from the pond skimmer then drops down to the pump thus trapping air in the pipe. You may be able to prime the pump two or three times to suck out all the air. If the problem persists, put a tee in the intake pipe at its highest point with the stem up. Reduce the opening to 1" and put in a ball valve. When you need to prime the pump, open the valve and fill the pipe with a garden hose. Having the tee at the highest point in the pipe allows a way for the air to get out. Be sure to close the valve when the pipe is full.

is a group of primitive single-celled plants. It can be spread in the air or through introduction of of plants, rocks etc. that have algae on them.

Algae comes in two primary types. Single-celled green algae turns the water pea soup green. Bearded blue-green algae (also called string or bearded algae) grows in long strings off the side of the ponds and rocks on the waterfalls. Both types are beneficial for the fish. The algae eat the nutrients in the water that would otherwise build up and become toxic for the fish. Some algae in normal, expected and beneficial for a pond and its inhabitants. Seldom are both type found in the same pond. Algae growth is directly proportional to the amount of nutrients available and the temperature of the water. A big source of excess nutrients is over feeding.
See the section about algae in the pond overview section.
To control algae is the goal of pond owners everywhere. We take a long term approach to control algae since we can not dose the water like we could in a swimming pool. It is important to start with the right equipment, including biological filter, aeration and an ultraviolet light (U/V). An U/V light will not eliminate algae, but will remove single celled algae leaving you with the bearded algae. Since having some algae is inevitable, we prefer to have the string algae over the pea soup algae because it generally leaves the water very clear.
As important as the proper equipment is to a healthy pond, maintenance is equally important. Regular maintenance includes cleaning leaf traps, back washing, adding bacteria, preventing and removing leaves and other debris form entering the pond. See Pond Maintenance.

Algicides should not be used in fish ponds because it very hard to figure the proper dose that is strong enough to kill the algae without harming the fish and plants.

Pumps lose some of their capacity to pump water at high elevations because the atmospheric pressure is less. At sea level, the atmospheric pressure, the pressure the air pushes down on the water is the pond, is 14.7 pounds. At 5000 ft elevation the atmospheric press is reduced to 12.0 pounds. Thus, for every 1000 feet of elevation, the pumps ability to draw water is decreased by 10%. So a pump that can draw water from10 feet at sea level can draw water only 5 feet at 5000 feet elevation. In higher elevations it is necessary to up size the pump (and reduce the head loss.


Automatic water fillers see POOL MISER



dosage dose will vary greatly from pond to pond and seasonally. We generally recommend backwashing and adding bacteria twice a week in hot months, once a week in moderate months and backwashing only during cold months. Bacteria do not do well in water cooler than 55° or so. This assumes you are here in northern California. In colder parts of the U.S., use winterizing instructions.

function see bacteria in Pond overview

see biological filtration in pond overview

is attached to the sand filter and directs the water flow, much like a conductor directs the orchestra. We recommend the six position backwash valves. See sand filter operations.
NOTE: Never turn the backwash valve with the pump running.

The six positions are:

  1. FILTER is the normal running position. Water enters the filter through the top, is filtered through the sand, is collected in the 8 or 16 laterals in the bottom of the filter and returned to the pond.
  2. RECIRCULATE is a test position. Water enters the valve and returns directly to the pond and does not enter the filter. If the water volume appears to decrease, turn the BWV to recirculate. If the volume returns, the sand in the filter needs work. See filter cleaning.
  3. CLOSED position does not allow water to move anywhere. You may use this position to prevent water coming out the leaf trap when cleaning it. NEVER have the BWV in the closed position with the pump on.
  4. BACKWASH reverses the normal flow of water in the filter. It enters the bottom through the laterals, pushes debris up through the sand, where it is collected in the top diffuser and goes out the waste pipe.
  5. RINSE collects water through the laterals, like the filter position, but sends it out the waste pipe.
  6. WASTE takes water from the pond and sends it directly out the waste pipe. Useful in draining the pond.

The dome of the filter is usually equipped with a pressure gauge and air relief valve. See pressure gauge.

Regular back washing is necessary for a healthy pond in order to remove excess nutrients and debris. How often you need to backwash varies greatly from pond to pond and seasonally for any pond. Here in northern California, we recommend twice a week in warm weather, once a week in spring and late fall and virtually never in very cold weather. Even this can vary greatly. See POND OVERVIEW
NOTE: In addition to back washing, you need to keep the skimmer and leaf traps clean.
NOTE: Never turn the backwash valve (BWV) with the pump running.

A typical backwash sequence is:

  1. Make sure water level is adequate for back washing.
  2. Turn pump off and put BWV on closed. If your equipment is lower than the pond level, you may have a ball valves to close.
  3. Clean skimmer basket(s) and leaf trap at the pump. Make sure the 'O' ring is clean and lubed and to replace water in leaf trap. Open the ball valve.
  4. If you have a valve on your discharge pipe, open it now. Turn BWV to backwash and turn pump on, use high speed if you have a two speed. You will probably run it for 20-30 seconds. Most systems have a sight glass in the BWV or a clear piece of PVC to allow you to see when the water clears up.
  5. Turn BWV to rinse and run pump on high for 20-30 seconds or until water in sight glass clears.
  6. If necessary repeat steps 4 & 5.
  7. Return BWV to filter and pump on normal operating speed.
  8. Open air relief valve on top of filter until a steady stream of water comes out then close.
  9. Add bacteria according to instructions on bacteria container and see bacteria information above ║ .




Cavitation is the creation of gases from turbulence similar to the trail found behind a boat propeller. Cavitation is often created when water passes through a 90° fitting. This is why we try to use as many 45° fittings as possible. Avoiding cavitation is very important as the water enters the leaf basket in front of the pump because the pump acts as thought there is an air leak and you can't find it.
Always use 4 times the diameter of the pipe in a straight run before the leaf trap. What this means in English is if you are using a 2" diameter pipe for your suction pipe, you should have at least 8" of straight pipe before it enters the leaf basket.





COST OF RUNNING AN OUT-OF-POND PUMP@ 10 cents per kilowatt hour
HP Hour Day Week Month Year
1/8 $0.0125 $0.30 2.1 9.1 109.2
1/2 0.05 1.20 8.4 36.4 436.8
3/4 0.075 1.8 12.6 54.6 655.2
1 0.10 2.4 16.8 72.8 873.6
1-1/2 0.15 3.6 25.2 109.2 1310.4
2 0.2 4.8 33.6 145.6 1747.2
3 0.3 7.2 50.4 218.4 2620.8



A civil engineering friend says his job is drainage, drainage and drainage. Drainage is important around and below the pond or fountain whether they be liner or concrete.

If a liner pond is to be installed in an area with heavy, clayey soil, put a french drain under the pond so accumulating water has a chance to run out. If water accumulates under the liner it will puch it up. It normally will go down when the water below the liner subsides but the puching may put pressure on tank fittings that pass through the liner. For you flatlanders, if the problem is severe, have the French drain empty into a sump (hole) with a pump with a float switch.

Drainage around the pond is also important. Grade the area around the pond so it is away from the pond. Even if the pond or waterfall is on a slope, contour the area or install French drains so runoff does not go into the pond.



If you don't know how to change an electrical outlet, don't wire your own pump. We do not attempt to teach basic electricity. We are trying to aid those who have an understanding of electricity and help them apply their knowledge to a pond or fountain project.

All external pumps and 120v lights should be properly grounded in accordance with manufactures' recommendations and local building code and protected by a GFI.

With the outragious cost of electricity these days, it is even more important to conserve electricity. When looking for energy saving (and money saving) measures, we should look at the operating and maintenance costs as well as the initial equipment costs and energy costs. What good is it to save $20 on electricity and to not have a balanced system that requires replacing the pump every three years, of less. The best way to save money is to have a well designed, well engineered and well constructed system.

Within a balanced system, there are several components we can examine separately. Most people think first of pumps when they think energy efficiency, and pumps are a very important component of energy saving. However, the way pumps save, or cost, us energy are not all obvious.

  • Pump Efficiency. Newer pumps, especially the Sta-Rite series, use about 30-50% less electricity to move the same amount as compared to old cast iron pumps. See the section on Horse Power.
  • Pump Size. Having the proper pump size is always best. A smaller pump that may save a few bucks on electricity may cost in the long run because of poor filtering, high maintenance demands and frequent pump repairs or replacements. Having a pump too big for the suction and return pipes is similar to having pipes too small to handle the amount of water necessary. Keep reading for pipe sizing.
  • Pump Type Out-of-pond pump are more efficient than submersible pumps of the same horse power rating.

A two speed pump has about a 70% energy saving as compared to a one speed. This is because we use the low speed for daily use and the high speed for max flow times and backwashing.

There are many other factors than just pumps that determine energy savings or loss.

  • Proper pipe sizing is also critical. Each pipe diameter has a maximum flow (gallons per minute) that can pass through it. Trying to push more water through than the pipe can handle only wastes energy and can actually decrease the flow.
  • Plumbing configuration. In addition to having the proper pipe size, having an efficient water flow is also dependent of the amount of 'spaghetti' in the pipes. this primarily means how many 90° elbow there are. Just a short example from the Zen and the Art of Plumbing section. A 1-1/2" PVC 90° elbow is over 3.5 times as resistant to water flow as a 45° elbow. Two 45° elbows close together are still about 1.8 less resistant. If the 45° elbows are further apart, they are even more efficient. The resistance from a single fitting may not be very important in the bigger scheme of things, but is possible that good plumbing practices can reduce the size, and expense, of a pump. In addition, good plumbing practices will help prevent pump damage.


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