What Horse Power Pump Should I get for my Pool?
When I first started in the pool business in 1976 most pools had 1/2 horse power or 3/4 hp pumps. Today most pools have a 1-1/2 hp or 2 hp pumps. Arrr Arrr Arr as Tim Taylor says, but is a larger hp pool pump always better? The pump manufacturer can manipulate the pump horse power by changing the service factor rating of the motor. You can actually have the exact same motor on a 1-1/2 hp pump as on a 2 hp pump.
Pool pumps should really be rated by the gallons per minute of water flow instead of the motor’s hp. You need a pump that will be able to pump all the water in the pool through the filter in 8-10 hours. Which is 40 gpm for smaller pools and 80 gpm for larger pools. When replacing a pool pump you should check the flow rate of the existing pool filter. The gpm of the pump will go down the farther away from the pool the pump is located. Valves and PVC turns will also restricts the pumps gpm.
Today in our green energy efficient world it is even more valuable 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 include a pump timer, 2-speed motor and the newer variable speed pumps. 
38 Responses on What Horse Power Pump Should I get for my Pool?
The diffuser of the 2-HP Astral pump fixed at our pool got damaged and the local agent does neither maintain spare parts on shelf nor bother to help with delivering such parts. What is the nearest Astral Pump Service Centre to contact re ordering a new diffuser?
Please advise
Some Astral parts are available online http://www.royalswimmingpools.com/Parts.htm
We can also order other parts as well
I agree with the above. Most people have way too big pumps for their pool. they end up being whirlpools, instead of filtering properly.
Our son has purchased several pools and was adamant that two 1 horsepower pumps installed in our new 400 square pool would save us energy. When we talked with the pool company, they led us to upgrade from 1 horsepower to 1 1/2 horsepower pump. Unfortunatley, when we got the specs from the engineer, they went down to a 1 horspower pump -supposedly to save us energy. What are your suggestions on 1 horsepower vs 1 1/2 horsepower in a 400 square foot pool?
On most installations one pump is better than two unless you need a booster pump for a water feature. Pool pumps should really be rated by the gallons per minute of water flow instead of the motor’s hp. PVC pipe size and distance must be considered also.
Great piece, simple and to the point. We run into a lot of overwhelmed filters. Way to many builders are flowing the water well above the filters max flow. Balancing filters and pump size seems to be a big mystery to a lot of pool professionals. Bigger isn’t always better especially when considering pool pumps. We do a lot of work with filters all over the world and it’s kind of the same story all over.
Jeremy
My pump has been making noises so i hired someone to come in this May to change it - i Have an inground pool that is 22×44 and 4ft to 8ft deep
I currently have a 1 1/2 pump and he wants to goto 2 horse power.
will this damage my pool pipes in any way
You will need to look at the GPM flow rate for each pump. If you have 2″ PVC pipe you may be fine. If you have 1-1/2″ PVC pipe the 2hp pump may have to high of a GPM rate for the PVC size.
Hi I have a question for an above ground pool. I have a 18 x 48 round pool. The pump and filter that came with it is no good. I want to replace with a sand filter system. What horsepower would I need? Would 1/2 be suffcient? Thank you, Kim
A filter system from 1/2 hp to 1hp will be good for an 18′ round pool http://www.royalswimmingpools.com/pumpfilter.htm
We bought a house that has an in-ground pool, 45 feet by 20 ft wide, about 3 ft deep to 7 or 8′ at the deep end. The pool has been sitting for months with no pump. What size pump should we buy for this pool? Everyone just wants to sell us and we don’t know who to believe. Thanks!
Dave, there are many great pumps to choose from. The first thing you need to know is what size plumbing you have on your filter. Most pools have 1 1/2″ or 2″. Horse power isn’t that big of a deal unless you have a lot of water features. The best selling inground pump is the Hayward superpump and most people go with 1.5hp.
Thanks, Johnny. My plumbing is 1.5. I have no special water features. Just a plain ole pool. The filter is a Hayward sand filter, diameter of 23 inches. Thanks for any additional wisdom you can share.
I have a pool 18 by 52 holds 8,119 gallons of water I have a 2hp pump sand filter how long should the filter be run and in what cycle in low or high most way to save money
I have a pool 18 by 52 holds 8,119 gallons of water I have a 2hp pump sand filter how long should the filter be run and in what cycle in low or high most way to save money
Giovanni, for residential pool you need to turn the water over 1 to 1 ½ times per day. Which means you will need to flow 8119-12178 gallon per day. The time per day will depend on many variables like how many gallons your pump will flow per hour, the amount of people swimming, how much sunlight the pool gets, and how you sanitize the pool. I would recommend running 6-10 hours per day and adjust based off need.
Norma, since you have a two speed pump, I would run on low speed because most pump use 1/8 of the electricity when you reduce speed by 1/2. 2 hp pump is a really large pump so the pool should be fine to run in low speed for 8-12 per day maybe less.
I have a 15 x 24 oval above ground pool, which holds approximately 9110 gallons of water. I had a Hayward 1 1/2 HP Pump and Filter. I needed to replace everything due to age. The dealer advised that I could go to a 2 HP 2 speed pump and filter. He advised me that he has sold the 2 HP pump for smaller pools also. Is this pump too large? I used to run the pump on low 24/7. But with this larger model, should I still be doing this?
Ann, it doesnt hurt to have a bigger pump if your filter can handle it however you don’t need it and would only need to run it maybe 8 hours a day. 2 hp pump will use more power normally so it will cost more to run it.
I have an 18000 gal inground pool with a spa and a waterfall that is about 3 1/2 feet above the pool surface. My pump is 2 1/2 HP with a Hayward C1200 cartridge filter. A person told me the horsepower is way too high for that filter, and it should be 1 1/2 HP. Looking at Hayward’s website they have pumps up tp 5 HP for that filter configuation. I think if I go to less HP the waterfall might not run properly. What is your opinion?
Debbie, 2.5hp is a large pump. I believe the filter is a little small however it should still work.
We are building a new pool with an attached spa. The pool is about 14,000 gallons. What difference should it make in the size of the pump with having a spa connected? Thanks!
Frank, the amount of jets and water flow requirements for the spa will make a difference. I have a 18,000 gallon pool with a spill over spa that has 8 jets and a 1.5 hp pump with 2″ pvc on the suction side. It works really well.
Yes I have the same size pool as Ann. 16×24 oval about 9100 gallons. I want to know whats the smallest horsepower pump I can use? I would prefer to run it on low 24/7 instead of 8 to 12 hours a day on high. It should filter about 13 gallons a hour but I can’t find what size pump that would be.
Kristie, That would depend on what brand and type pump. You will need to turn the water 1-1.5 times per day. That means in 24 hours you need to flow 9100-13650 gallons. So you will need a pump that flow at least 379-568 per hour. That would be a really small pump most pumps flow at least 5-10 times that.
Hello, I have a smaller inground pool with a small spa attached. The spa only has 4 jets. We currently have a 1.5 hp pump that is ready to be replaced. My problem is when I run the pump for just my spa the pressure skyrockets from 10 psi to 30+ psi. Is my pump too high in hp and that is what is causing this problem. Should I replace it with a smaller pump? My plumbing is 1.5 inch.
I have a pool thats approx 44 ft x 16 ft, 9 feet deep, its a 2 pump setup, filter side is a 2 hp with 1 1/2 piping, the jetts for the spa (jets only) 4 jets, has a seperate pump, its from the early 70’s and a 2 hp with 2 inch piping, i dont know any of the ratings as there warn off, i want to get a newer pump and have a extra 1.5 hp sta rite pump and its gpm is around 60, depends on the run. will i see a improvement over the old? or will i see any difference? should i go with a 2 hp?
I have a 24′ round pool. I bought an energy efficient 1/2 hp pump to replace my 1 hp 25yr old Jacuzzi that finally gave up the ghost ( a GE motor, by the way)…what a great old pump. Anyway, the 1/2 hp gives me just as much power and return flow as the 1 hp did. Trust me, I have had this (used) pool for 17 yrs. I plan to move the pump farther away from the skimmer and return. I will have no problem , as it is a really stong motor. From poolbargains.com,$137. Hope I get even half as many years out of it as I did the old one!
Ok I have a 33 round above ground pool. 27,500 gallons of water.. anyway my pump has a sand filter and the one that broke was 2.5 horse power. what do u reccommend. im clueless
Hi Scott, I have what may be often described as a Garden Pool. 18′ round 4′ deep fiberglass in-ground 2 inlets, one skimmer in pool plus inlet to a very large waterfall. I had a Sta=rite 3/4 hp pump w/ 18″ sand filter. The water fall 3′-3-1/2′ above water level hooked to filter. NOT a very good flow but still kept pool realitively clean. I was told to get 1 1/2 hp to accomidate the water fall flow which I did looks great! but too big for the filter, 30+psi ! water is cloudy what size filter should I get?
Sandra, I would reccomend a 24″ sand filter. We have many options to choose from on our site. http://www.royalswimmingpools.com/ING-pumpfilter.htm
Have a 30,000 gallon in ground pool. My motor burnt out and was just replaced. The connector was burnt. It was only 5 years old. It was a 1.5hp and the new one is 1.0hp. The pump was not changed in the process. The new motor gets pretty hot and shuts off and after a few minutes goes back on. Is this an electrical issue as I had the hurricane and it impacted the power in our area. The pool circuit breakers are not tripping. Everything in my home still works fine.
Most likely you need to change your impellar. The rule is when you go to a bigger hp motor you always have to put a bigger impellar on. Otherwise it will do exactly what your describing. It running hot, tripping the thermal switch and shutting down. Then when it cools it will start over. 9 out of 10 times you dont have to change the impellar when downsizing motors, but this isnt always the case. You need to research what size impellar fits your pump for that hp and sf motor.
Help? I have been researching a new pump. I have a 24,000 gallon pool,buil in spa-fountain, 4 total 2 inch returns, a heater and a cleaner with booster and a 72 Sta-rite DE filter. Longest pipe run is 106ft, shortest 55ft and the others 70ft, replacing a 2hp Sta-rite….factor 1.1……I almost pulled trigger on SP4020 Hayward Northstar- full rated 2hp X 1.20= 2.4, but I found a SP4015 Northstar - max rated 1.50hp x 1.60= 2.4..are these motors the same thing? What will be the actual difference for me? thanks, Jeff Seger Texas
With a 24,000 gallon pool you you need an 8 hour turnover rate. In order for you to do that you need a pump with a 50 gpm flow rate. The length of your pipe does not matter so much as the size of your pipe. 1.5 inch pvc will only allow 42 gpm to flow, so even if you have a pump that can move double that it will do you very little good. Im assuming since you have 2″ returns that you have all 2″ plumbing. 2″ pvc allows 73 gpm. We will also ASSUME your pool has a TDH of 50-60. So all you need to do is to look at the pumps maximum flow rate to determine what hp you will need. Different brands have different pump curves so you cannot rely on hp alone. When you decide what brand you want to go with look at a comparison chart to see which hp you will need per that brand pump. Choosing the correct pump for your pool will save you money on electricity and wear on all your other equipment.
Thanks, I went with the Hayward Northstar 2.0 hp per flow rate need. I appreciate your response, thankfully it confirms my decision.
I have a 16 x 32 ft inground pool. My pump is 1.5 hp. I was told that a Hayward 24 inch sand filter will work, but then I was also told, by someone else, that my pump is too big for that size filter. I don’t know what to believe, can you help me out?
Thanks!
I would need to know alot more info than just the hp. Different brand pumps have different pump curves. For example a Pentair Whisperflo 1/2 hp pumps more water than a 1hp jandy pump…ect.. You will need to research what you need your turnover rate to be for your size pool. Then you need to determine how many gpm your pump moves and then you can determine which size filter you need. If you read my previous post on 10/12 explaining a bit about about TDH and flow rate it may help you out a bit.
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