If you're looking to build a new pool or simply looking to replace a pool pump you may find yourself asking, "Is a larger horsepower (HP) pool pump always better?"
For example:
√ If choosing a pump with a 1-1/2” inlet/outlet, you should choose a filter with a 1-1/2” inlet/outlet as well. However, a pump with a 1-1/2” inlet/outlet can work with a filter with a 2” inlet/outlet if needed to.
X You would not want to attempt to use a pump with 2” inlet/outlet with a filter that has a 1-1/2” inlet/outlet as they would not be sized correctly or efficient when used together.
You can also learn more about Single Speed and Variable Speed Pumps Here!
IMPORTANT INTERRUPTION: Due to the rise in demand caused by the 2020 pandemic, pools in general are experiencing delays in manufacturing and shipping. If you are looking to buy a new pool in the next few years you may have a longer wait time than anticipated. It's important to shop early. While pools traditionally purchased in the Spring or even late Summer can usually have many weeks of use that same year, the entire industry is currently delayed by several weeks and in some cases several months. That's on the manufacturers side of the business. Most pool builders are booked 6-12 months out presently. The best plan you can have is to purchase your pool at least 3-6 months before you'd like to start building. More on purchasing a pool during or even post-pandemic can be found here. Now back to choosing the best pool pump for you.
While outside of this simple yet extremely import we get asked a lot about what HP a pump should be. That being said, it's important to know that pool pumps should really be rated by the gallons per minute of water flow instead of the motor's HP.
What you're looking for is a pump that will be able to pump all the water in your pool through the filter in no more than 8-10 hours. This typically looks likes 40 GPM (gallons per minute) for smaller pools and 80 GPM for larger pools. However, you can determine the more precise needs of your individual pool by following these steps:
Keep in mind that the desired time frame of turnover is between 8-10 hours, so you get a range by substituting the 8 hours used above, for 10 hours instead. This would allow a range of acceptable pumps instead of assuming only one options.
Your pool pump's GPM will directly relate to your pool's filter GPM. You'll want your filter's GPM to be higher than your pumps to alleviate any additional strain on the pump motor.
While some may think it's just easier to go with the highest GPM and HP and not worry about anything further, note that your pool's pipes can only take so much movement and pressure based on their size. For this reason, each pool has a maximum flow rate, which is determined solely by your pool's pipes.
This means that you can have a pump capable of moving 100 gallons of water per minute, however, if the 1.5-inch piping will only allow 42 gallons per minute you risk damaging your system by creating too much strain on your pump that cannot move water as quickly as it'll be trying to.
Your pool will most likely have multiple sizes of piping. You'll want to err on the side of caution and use the smallest piping for your pool's maximum flow rate. For example, if you primarily have 3-inch pipes in the plumbing system of your pool, but also have a spa with a 2-inch plumbing pipe, you're maximum flow rate would be 73 GPM.
There are ways to get the most gallons per minute from your pool pump with the least horse power motor. Increasing the PVC pipe size from 1-1/2" to 2" will increase any pumps GPM. Other options to make your pool pump more efficient are:
For more on Pumps, like the difference between single, two or variable speeds, try this article!
Additional resources for your pool buying journey: