FAQ - Pumps
From the smallest barrel garden to the largest Koi pond, no water garden can survive for long without water movement. It should go without saying that for water movement, a pump is essential. The pump has been called the 'heart of the pond' because circulating the water keeps the pond healthier than it would be if it were stagnant. In addition, the movement of water through a stream or over a waterfall can provide many of a pondís most remarkable features. A cascading, bubbling stream adds interest to a garden, while a waterfall can create a dramatic centerpiece. Fountains provide architectural or thematic accent to a scene, and provide the additional benefit of aereating the water, something that is essential to providing a healthy environment for fish. There are two kinds of pumps in the world, submersible and non-submersible. Submersible pumps range in size from tiny fountain pumps to large industrial pumps that move water on a grand scale. For most of us with average sized ponds, there are many pumps available. My criteria for selecting a pump are, 1. Does it have the desired capacity?; 2. What sort of intake and outflow ports does it have? I want them to be standard pipe threads, not some off-brand or custom thread that canít be used in any way other than that intended by the manufacturer. In other words, I donít want to be compelled to use only that manufacturerís accessories. With standard pipe threads, you can do anything that you like with the intake and the outflow. Submersible pumps rarely pump more than 1500GPH, and so are useful for small to medium sized pond systems. Among those that are not submersible, there are two types, self-priming, and non-self-priming. Self priming pumps are useful when the pump has to be mounted above the water line in the pond. Non-self-priming pumps will not pull water up hill, but they are very good in situations where the pump is mounted well below the water line. Both types of pumps are usually manufactured for pools, but in a case of the industry catching up with the hobby, there are now a plethora of good, highly efficient pumps available. Pumps have, in general, become more efficient, quieter, and with a greater range of capabilities and accessories in recent years, which is all to our benefit.
To maintain a healthy pond, experts recommend that the water be circulated once every two hours. At the very least the water should be fully circulated two or three times per day. That means for a 1000 gallon pond you would need to pump at least 500 gallons an hour through the pond to recirculate it in two hours, hence a 500 GPH pump or larger would be needed. Other factors to consider include how much water should be circulated through the filter and what is required to make your waterfall or fountain look right; how high the water is to be pumped, and how much pipe it will have to go through.
The higher a pump must push the water, the less water will be pumped. The term 'head height' is used to indicate the rise, measuring how high the water must be pumped for a particular application. Every ten feet of tubing the water has to be pumped through adds resistance equal to one foot of rise, further reducing the water flow.
When selecting a pump, look for the gallons per hour for each head height, as well as the maximum height the unit will pump. At maximum height' (max head), the pump will probably only put out a trickle of water. Be sure to get a pump that is suitable for your water garden. Nearly all pumps come with information that will tell you what their capabilities are.