There are many factors to consider when choosing a pond pump. The size of the pond or water feature, whether there are fish present, desired effect, and budget are just a few. I am assuming that you are a first-time pond builder so I will discuss primarily submersible pumps. A submersible pump is one that stays in the water and pumps water up through the water feature. Submersible pumps are generally used more in your smaller to medium sized ponds. These pumps can start out at 100gph (gallons per hour) for a small fountain, and go up to 3,200gph for a pretty good sized pond and waterfall.
How Big is Your Pond
The size of the water feature is a good place to start when trying to determine which size of pump you need. It is pretty common to want your water to cycle at least once an hour. I recommend twice an hour if possible and practical. Sometimes a really heavy water flow is a bad thing. Case in point, I like a really heavy water flow but one of my ponds is only about 180 gallons and it is outside my daughter’s bedroom window. The pump I am running in it is about 2,200gph so the noise of the waterfall has woken her up in the middle of the night. You also need to consider the types of plants when running a heavy water flow as it can hold some floating plants on one side of the pond or beat the heck out of a prized water lily.
Bigger is probably Better
Let’s say that your pond is going to be 500 gallons. We can assume that you need at least a 500gph pump if you want to cycle the pond at least once an hour but it is improbable that this pump will be large enough. If you intend to have a waterfall you will have to consider the amount of gph that you will lose to lift the water to a certain height. When you buy a pump and it claims to pump 1,000gph they are generally indicating that amount at head height or right at the pump. A standard pump that pumps 2,400gph at the head will only pump approximately 1,800gph at a height of about 5 ft. Other considerations would be the size of pond hose and how far the pump is pushing the water. So you see it is easy to buy a pump but we need to think a bit to ensure that we buy the right pump.
The Desired Effect
Now let’s talk about the desired effect. I like to work with my customers on this as it is rarely thought of when purchasing a pump. Many will factor cycling the pond, but forget what the end result will look and sound like. This is a trick I use to determine the effect. I take a garden hose turned on at full and let the water flow down the water feature. If I look at that and I decide that I would like five times that water flow, I now have a starting point. Next, I grab a five-gallon bucket and a stop watch. I fill the bucket to capacity and time it. If you fill the bucket in two minutes the hose would be pushing 150 gallons per hour. You initially determined that you would like five times that amount so now you know that you need a pump that will produce 750gph at the height of your waterfall. Remember to consider the restriction induced by the filter, size of pond hose, distance being pumped, and the head height as these all are going to be a part of the equation.
Budgeting for a Pond Pump
Let’s talk about the budget. I know that there is only so much that you had planned to spend on this pump now but you need to consider the future as well. If you buy an inefficient pump you will pay more for electricity eventually than you did for the pump. This is why at Zamzows we offer the Laguna line of submersible pumps. These are not only affordable they are very energy efficient.
A large Laguna pump that is pushing 2,500gph is only using the same amount of energy as a 100 watt light bulb. How about the warranty and serviceability of the pump? Laguna is beating everyone else there too! For your 500 gallon pond, I am recommending that you start with at least a 2,000gph pump. This pump would accomplish the water cycling needs of your pond, and the aesthetic looks you are going for. By going bigger than you need you can always divert some of the excess water being pumped and be allowed to change or enlarge the pond or water feature without buying another pump. Believe me, I started with a 125-gallon pond and got hooked enough that my new 3,000-gallon pond will be finished this spring.