Water features should be designed for energy efficiency and ease of maintenance. Once you have decided on a location for the water feature, think about the best place for the equipment, too. This does require some serious attention because the best balance between how it will look and sound, and how well it all works together is not always apparent at first.
The main components of the water circulation system utilizing a centrifugal pump are: main drain (intakes), pond skimmer, pump and strainer (leaf trap), filter, u.v. sterilizer, return line. If there is only one main pond intake, it should have an anti-vortex cover to protect people, and fish, if any are planned, from the strong pull of water through it. It is better and safer, however, to have at least two main intakes in the bottom of the pond. That way if one becomes blocked or obstructed, water continues to flow through the other one. If the pump is below the waterline, install a gate (ball valve) just before the pump strainer to hold back the pond water while the strainer basket is being emptied and cleaned. The pump strainer catches any debris pulled in through the main intake before it reaches the impellar.
The pump and other equipment can be below water level if desired, creating a condition known as flooded suction. This means that instead of having a high amperage pump to create suction to pull water through the main intake in the pond, your pump will already be flooded with water inside the impellar. This way you can get by with a lower amperage pump, and that means less noise and power consumption.One design to enable the pond pump to have flooded suction is to have the walls of the pond raised above ground eight or more inches. Another design is building a below ground level (and water level) pump house, but it must be made rain proof and flood proof. As a precaution, install a 3” or 4” drain and line inside leading away from the pump house.
What to do if the pond edge is at ground level, and the pump is above that level, as is often the case? We create an artificial water level in our intake line by installing a swing check valve a few inches below the water level of the pond. Ideally, the valve on a 2” intake line would be a 2 1/2” or 3” “true union” swing check that is installed “downhill” at a 45 degree angle. The body of a true union swing check valve is replaceable without cutting the main intake line and glueing in a new valve. It should be positioned in an access box underground in front of the pump.
To increase system efficiency, cut down on flow resistance (friction loss) when water is flowing through the suction and return lines by using at least 2" pipe, and as short runs of pipe as possible and as few 90 degree fittings as possible. One 90 degree fitting is equal to about 10 feet of the same size pipe in friction loss. One example for reducing friction loss is instead of 90 degree fittings, use two 45 degree fittings, or 90 degree “long sweeps”, which are available in schedule 40 PVC pipe.
The size of pump you use is also contingent on whether or not you have plants and fish. If you don’t, and it is strictly ornamental in nature, size the pump to achieve the effect you want with your waterfall. In this case power usage may not be as much because the system is only running four to six hours a day. The pump will need to run long enough each day to cycle the water through the filter a number of times. When I say cycle I mean the water is completely recirculated one time. Anyway, the only other time you need the pump running is to run your waterfall. The pond pump must run continuously if it is maintaining a fish pond. Either way, you want to use the smallest pump you can to do the job, or at least a high quality, energy efficient pump. When choosing pumps, or any other equipment for that matter, please decide what your requirements are and then obtain the specifications you need from the equipement manufacturer or supplier. Although there are several ways of putting together these systems, they all work on the same basic principal.
The next major component in the water circulation system is the filter. This is another area which is again dependant on whether you have living things in your water feature. If you don’t, then use a cartridge filter. The size of this will depend on the size of the pond, where your equipement is and how well you can hide it all. With natural water features you must hide or disguise your equipement. For water features with plants and fish, (after testing many different fiters and methods over twelve years), Aqua Ultraviolet bio-filters are the only ones I install, period. Always install a good quality ball valve in line between the pump and filter. That way you can slow down the flow of water to the filter if necessary to let it work more effectively. The ball valve can also help control excessive splashing out of the boundaries of your waterfall therefore cutting down on water loss.
There are a few more things we need to add to our water circulating “loop” after the filter. One is a check valve, which keeps the water in the return lines from draining out when the pump goes off due to a timer shutoff or if shut off manually. The check valve reduces the work load a little for the pump every time and also prevents a loud gurgling noise from occuring every time the pump is turned on and is pushing air and water up through the return line, especially on the taller waterfalls.
After the filter and check valve comes the ultraviolet sterilizer. The u.v. sterilizer is a must for live ponds; optional but recommended even for water features without plants and fish. Depending on what size unit you use, it can greatly reduce or eliminate the need for chemicals such as chlorine or bromine in ornamental ponds. U.V.’s kill free-floating algae spores, parasites, and bacteria harmful to fish and people.