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Your first step is to determine the number of gallons of water in your pool. The formulas for calculating the gallons depend on the shape of your pool.

Measure the length (ft), the width (ft) and the average depth. The average depth is determined by adding the depth at the shallow end to the depth at the deep end and dividing by two.

The formula for calculating the total gallons in a rectangular pool is

Determine the number of gallons of water in your round pool, measure the diameter of the pool and its average depth. The average depth is determined by adding the depth at the shallowest part to the depth at the deepest part and dividing by two.

The formula for calculating the total gallons in a round pool is

To determine the number of gallons of water in your oval pool, measure the longest diameter, the shortest diameter, and the average depth. The average depth is determined by adding the depth at the shallow end to the depth at the deep end and dividing by two.

The formula for calculating the total gallons in an oval pool is:

To determine the number of gallons of water in your kidney-shaped pool, measure the largest width, the smallest width, and the average depth. The average depth is determined by adding the depth at the shallow end to the depth at the deep end and dividing by two.

The formula for calculating the total gallons in a kidney-shaped pool is:

For example (see picture): Your pool's length is 25 ft, longest width is 15 ft, shortest width is 10 ft and the pool's average depth is (3 + 7) / 2 = 5 ft. The pool's capacity is (15 + 10) x 25 x 5 x 3.38 = 10,563 gallons.

Now that you have calculated the number of gallons in your swimming pool, you want to **determine the required gallons per minute (GPM)** you need to a pool pump to clean all the water in your pool in eight hours. To come up with this flow rate, simply divide your calculated gallons by eight.

**For the Rectangular pool example**, the GPH required is 20,250 gallons / 8 hours or 2531 GPH.

Most pool pump specifications are expressed in gallons per minute (GPM). So, to convert from GPH to GPM, divide your GPH by 60 minutes - 2531 GPH / 60 = 42.2 GPM.

**Click Here to View Inground Pool Pumps**

Most pool pump specifications are expressed in gallons per minute (GPM). So, to convert from GPH to GPM, divide your GPH by 60 minutes - 2531 GPH / 60 = 42.2 GPM.

Having calculated your required GPM, you next have to figure out the average Feet of Head for your pool pump.** Check out our blog on How to Calculate Feet of Head**.

***Please note, we are currently reviewing our procedure for estimating feet of head. Current estimates are too high***

You now have the information required to select the size of your pool pump. Go to the description page of the style of pump you would like to purchase. Many pump manufacturers will provide a chart on this description page showing the HP required for your particular GPM and Foot of Head. For example, say you wanted the popular Hayward Super Pump (an abbreviated version of the Hayward Super Pump performance page is shown at the left). Based on the data calculated above for a typical RECTANGULAR pool, we are looking for a pump that will handle 42GPM with a 47 Feet of Head. According to the chart for 50 Feet of Head (closest to 47'), we need a pump between 3/4 HP (31 GPM) and 1 HP (50 GPM). Since we always go for the higher GPM, we would select the 1 HP pump.

The full performance page for the Hayward Super Pump can be found at this link, **Hayward Super Pump**. For the location of performance pages for other pump models, contact an Inyopools sales representative at 1-877-372-6038.

The size of your pool filter is directly related to the pool pump you have selected. If your pool filter is too small for the pump, there will be additional strain on the pump motor as it tries to push water through and encounters resistance at the filter. This will eventually burn out the pump motor and your filtration will also be compromised. We recommend selecting the filter so that it is oversized to be absolutely certain it can handle the flow coming from the pump. So, in this case, instead of getting a filter rated at exactly 42 GPM, you should select one that is a little higher – around 60 GPM would be fine.

There are a couple of other considerations that should be mentioned in your selection of a swimming pool pump. The above calculations are based on a basic pool configuration with no extra water features like: fountains, spas, waterfalls, solar heating, and in-floor cleaning systems. These features generally require higher GPM rates which equate to a higher HP pump. Also if your pool requires greater than 60 GPM you may need at least 2" diameter suction pipes. Suction pipes of 1 1/2" have a physical limit of 60 GPM. 2" pipes can handle up to 100 GPM.

ChrisPosted: 6/3/2016Reply

InyoPools Product Specialist

Chris - For your size pool and water accessories, I would recommend one of two size pumps. If you have 1 1/2" piping, I'd go with a 1 1/2 HP pump. If 2" piping, go with a 2 HP pump. One pump should be able to handle your pool requirements. We have a series of new pumps we are recommending for quality and savings: the PureLine Pure Water Pool Pump 2 HP -PL3503 and the PureLine Pure Water Pool Pump 1.5 HP - PL3502. There is some confusion in the HP descriptions. The PL3503 is 2 HP not 1 HP, and the PL3502 is 1 HP not 3/4 HP.Dennis R.Posted: 6/2/2016Reply

ChrisPosted: 6/1/2016Reply

InyoPools Product Specialist

6000-gallon pool - Here a link to a VS pump that would better suit your small pool needs: Hayward Super Pump VS Variable Speed Pump (115V) 0.85 HP. If your pool system needs a stronger pump for jets, water features, look at this new Prime Variable Speed Pool Pump 1.65 HP. Great quality and price.Dennis R.Posted: 5/31/2016Reply

InyoPools Product Specialist

BM11 - For your ~26,000-gallon pool, I would recommend a mid-size VS pump like the new PureLine Prime Variable Speed Pool Pump 1.65 HP.Dennis R.Posted: 5/31/2016Reply

AnonymousPosted: 5/30/2016Reply

InyoPools Product Specialist

Susan - Susan - The humming you hear from your motor is most likely due to the start capacitor going bad. To check this capacitor and possibly replace it, see our guide on “How to Replace a Pool Pump Capacitor”. For you size pool, I would stick with the 1 hp pump/motor.Dennis R.Posted: 5/30/2016Reply

InyoPools Product Specialist

Motor humming – The humming you hear from your motor is most likely due to the start capacitor going bad. To check this capacitor and possibly replace it, see our guide on “How to Replace a Pool Pump Capacitor”.Dennis R.Posted: 5/30/2016Reply

InyoPools Product Specialist

Dave – Do you have diverter or ball valves to regulate water flow to your waterfall or are they taking the full pressure from your 2 HP pump. If the water flow is not being regulated and you replace the 2 HP pump with a 1 HP pump, will you be satisfied with half the waterfall length? If they are being regulated, how close are the valves to being fully open? Half way would be equivalent to a 1 HP motor.Dennis R.Posted: 5/30/2016Reply

BM11Posted: 5/28/2016Reply

SusanPosted: 5/25/2016Reply

AnonymousPosted: 5/25/2016Reply

DavePosted: 5/24/2016Second question. I have the same 2hp Northstar pump for my water feature, which is 2 - 18" slit waterfalls. I think that is overkill as well. Since it's only a feature with no cleaning or filtering duties, could I use a 1hp single speed? While I can look at the pressure gauges (filter and pump), not sure how I could determine the needed HP necessary so that I still have waterfalls and not just trickles, especially since I will most likely have to do some PVC re-routing for a smaller pump.

Reply

InyoPools Product Specialist

john mac - For your size pool with spa, I would definitely go with the larger 3.0 HP VS motor.Dennis R.Posted: 5/23/2016Reply

john macPosted: 5/22/2016Reply

InyoPools Product Specialist

Dave - Generally a 2 HP pump is larger than you need for a 13,000 gallon pool. I would go with the 1.5 HP VS pump.Dennis R.Posted: 5/10/2016Reply

DavePosted: 5/10/2016Reply

InyoPools Product Specialist

Steve - No, you do not need to make any other system upgrades to convert to a VS pump. It is a relatively easy process.Dennis R.Posted: 5/9/2016Reply

InyoPools Product Specialist

Homerun - If you downsized your motor from 1 HP to 3/4 HP without changing the impeller, you may be overloading your motor severely. The impeller is trying to move as much water as it did with a smaller motor. Check if you need a smaller impeller, and if so, replace it. Or, for your size pool, a 1 HP motor is generally what's required to move that much water. You might consider going to a 1 HP motor.Dennis R.Posted: 5/9/2016Reply

InyoPools Product Specialist

Willis258 - Sound like you have a 30,000 gallon pool. I would use 2" or 2 1/2" pipe where you can. Also, for your size pool, I would consider a large variable speed pump. You can save up to 80% on operation costs. Here is a guide on what you might consider for the circulation function of your pool - "How To Set Up In Ground Pool Equipment - Part 1 - Circulation".Dennis R.Posted: 5/9/2016Reply

StevePosted: 5/8/2016Thanks,

Reply

HomerunPosted: 5/8/2016Reply

Willis258Posted: 5/7/2016Reply

InyoPools Product Specialist

Windy Miller - Sounds like your proposed pool size is just over 100,000 gallons. So you are going to need as large a pump and filter as you can get. And you may want to split your pool functions into two systems: one for basic circulation and one for water features. See our guide on "How To Set Up In Ground Pool Equipment - Part 0 - Overview". This series of guides was based on a 30,000 gallon system so you may have to get larger equipment or run it longer. I would get the largest Variable Speed Pump you can find like the Sta-Rite INTELLIPRO VARIABLE SPEED ULTRA ENERGY-EFFICIENT POOL PUMP. On the cartridge filter, look for maximum sq. ft. filtration and GPM flow like the Jandy 4-cartridge system shown in the guide.Dennis R.Posted: 5/4/2016Reply

Windy MillerPosted: 5/2/2016Reply

InyoPools Product Specialist

les gideons - Here's a link to our best priced 2 HP in ground pool pump - PureLine Prime Pool Pump 2 HP. Shipping is free. Total cost is $399.Dennis R.Posted: 4/19/2016Reply

les gideonsPosted: 4/19/2016Reply

InyoPools Product Specialist

lovesbiddy - I would replace your current pump with one that has the same HP and SF. See our guide on "How To Understand True Pump Horsepower - Up Rated vs Full Rated". Pool heaters will shut off at 20 to 40 GPM depending on the make and model of heater.Dennis R.Posted: 4/14/2016Reply

lovesbiddyPosted: 4/13/2016Reply

InyoPools Product Specialist

LuvMahPool - It sounds like most of your piping is 1 1/2" so I wouldn't go with a much larger pump. Variable speed is good. You can recoup most of your initial cost with an up to 80% reduction in operating cost. For a great price on great quality, I would recommend the newer "PureLine Prime Variable Speed Pool Pump 1.65 HP".Dennis R.Posted: 4/13/2016Reply

LuvMahPoolPosted: 4/11/2016Reply

InyoPools Product Specialist

scpoolguy - I would recommend a 1 HP pump with 2" piping.Dennis R.Posted: 3/18/2016Reply

scpoolguyPosted: 3/15/2016My questions are=

1. What size pump should I use?

2. What size piping should I use?

Reply

InyoPools Product Specialist

Wai Kane - Glad to help. If you have a rectangular pool, you multiply the pool's length times it's width times its average depth. That will give you your pool's cubic feet. There are 7.5 gallons of water in a cubic foot so multiply your pool's cubic feet by 7.5 to determine its total gallons. See step 1 of this guide for an example of this calculation. GPM is Gallons Per Minute. You get this number by dividing Gallons Per Hour (GPH) by 60. See Steps 5 and 6. Also, if you would like to see what steps a builder goes through to build a pool, see our guide on "How To Build an In-Ground Pool".Dennis R.Posted: 3/7/2016Reply

InyoPools Product Specialist

wahoo - You may well have a leak around you skimmer. As an older pool shifts in the ground over time, it may cause a crack in your skimmer around the piping. Installing a new motor and pump will not fix this problem if that is what you are suggesting, but it sounds like you are due for a new pump. The energy usage for your pool is the same with 110V or 220V.Dennis R.Posted: 3/7/2016Reply

Wai KanePosted: 3/6/2016I'm trying to understand how to build a pool, not that I will build one, but just so I have some education on building one when I hire someone.

My question is how do you get the last calculating factor to figure out the amount of gallons?

LxWxDx? = GPH

Also, what does GFM mean?

Thank you once again for your educating me.

Reply

wahooPosted: 3/5/2016110 volt,1 1/2 pipe,hayward DE filter.

Might have leak in skimmer. When I install kreepy K hose and plate, It creates a air bubble under plate,even though it is under water.

Can i install just a new motor and pump?

Does it make sense to go to 22o volts?

Reply

InyoPools Product Specialist

ekh443 - A 1 1/2 HP VS pump should be adequate for your size pool if you don't have a lot of extra features.Dennis R.Posted: 3/4/2016Reply

ekh443Posted: 3/2/2016Reply

InyoPools Product Specialist

faceache - Your pump is the right size for your system. Your suction cleaner should work at around 2400 RPM and the Spa should run well at full RPM, 3450. It sounds like you have a low water flow problem. See our guide on "How to Correct Low Water Pressure in Your Pool System". A clogged impeller is a common problem.Dennis R.Posted: 3/1/2016Reply