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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.

For a RECTANGULAR 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: Gallons = Length x Width x Average Depth x 7.5.

For example (see picture): your pool is 30 ft long and 15 ft wide. The pool's shallow end is 4 ft and its deep end is 8 ft. So, the pool's average depth is 4 plus 8 = 12 divided by 2. This gives you 6 ft. The pool's capacity is 30 ft x 15 ft x 6 ft x 7.5 = 20,250 gallons. Go to Step 5.

For a RECTANGULAR 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: Gallons = Length x Width x Average Depth x 7.5.

For example (see picture): your pool is 30 ft long and 15 ft wide. The pool's shallow end is 4 ft and its deep end is 8 ft. So, the pool's average depth is 4 plus 8 = 12 divided by 2. This gives you 6 ft. The pool's capacity is 30 ft x 15 ft x 6 ft x 7.5 = 20,250 gallons. Go to Step 5.

For a ROUND SWIMMING POOL:

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: Gallons = Diameter x Diameter x Average Depth x 5.9.

For example (see picture): your pool is 25 ft in diameter, the pool's shallow end is 3 ft and its deep end is 7 ft. So the pool's average depth is 3 plus 7 = 10 divided by 2. This gives you 5 ft. The pool's capacity is 25 ft x 25 ft x 5 ft x 5.9 = 18,428 gallons. Go to Step 5.

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: Gallons = Diameter x Diameter x Average Depth x 5.9.

For example (see picture): your pool is 25 ft in diameter, the pool's shallow end is 3 ft and its deep end is 7 ft. So the pool's average depth is 3 plus 7 = 10 divided by 2. This gives you 5 ft. The pool's capacity is 25 ft x 25 ft x 5 ft x 5.9 = 18,428 gallons. Go to Step 5.

For an OVAL SWIMMING POOL:

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: Gallons = Longest diameter x Shortest diameter x Average depth x 6.7.

For example (see picture): Your pool's longest diameter is 25 ft, shortest diameter is 15 ft and the pool's average depth is (3 + 7) / 2 = 5 ft. The pool's capacity is 25 x 15 x 5 x 6.7 = 12,563 gallons. Go to Step 5.

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: Gallons = Longest diameter x Shortest diameter x Average depth x 6.7.

For example (see picture): Your pool's longest diameter is 25 ft, shortest diameter is 15 ft and the pool's average depth is (3 + 7) / 2 = 5 ft. The pool's capacity is 25 x 15 x 5 x 6.7 = 12,563 gallons. Go to Step 5.

For a KIDNEY-SHAPED SWIMMING POOL:

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: Gallons = (Longest width + Shortest width) x Length x Average depth x 3.38.

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.

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: Gallons = (Longest width + Shortest width) x Length x Average depth x 3.38.

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 how many gallons per hour (GPH) you need to 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 swimming 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.

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 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.

GregoryPosted: 7/15/2019 LatestReply

InyoPools Product Specialist

I would just buy a sump pump, since that's what it is meant to do instead of trying to repurpose a pool pump.Matt S.Posted: 7/15/2019 LatestReply

LizPosted: 7/12/2019 LatestReply

InyoPools Product Specialist

For a pool that size, you would need at least a 1 horsepower pump. This guide goes into more details about sizing speciically for above ground pools: How To Size an Above Ground Pool Pump and Filter SystemMatt S.Posted: 7/16/2019 LatestReply

CarolPosted: 7/4/2019Reply

InyoPools Product Specialist

I would go with the 2.7 HP variable speed to have the extra filtering rate just in case.Matt S.Posted: 7/9/2019Reply

Above ground pool pump sizePosted: 6/27/2019Reply

InyoPools Product Specialist

I would need more of the criteria we mention in the article to make an adequate guess.Matt S.Posted: 7/3/2019Reply

DougPosted: 6/15/2019Reply

InyoPools Product Specialist

You can stay with the 3/4 HP or you can upgrade to a variable speed which will provide maximal utility savings. The PureLine Prime Variable Speed Pool Pump 1.65 HP can be throttled to match your desired flow rate for any need.Matt S.Posted: 6/20/2019Reply

ScottyPosted: 6/5/2019Reply

InyoPools Product Specialist

Great question; the answer can be found here: How To Size an Above Ground Pool Pump and Filter SystemMatt S.Posted: 6/6/2019Reply

gerard eslerPosted: 6/29/2019Reply

InyoPools Product Specialist

The Pureline Prime 2.7 HP Variable Speed, and the Star Clear Plus 175 Sq Ft. 2 Inch Ports.Matt S.Posted: 7/9/2019Reply

KirbyPosted: 5/27/2019Reply

InyoPools Product Specialist

As step 10 mentions, the size of the filter is an important thing to know when sizing a pump.Matt S.Posted: 5/30/2019Reply

GregPosted: 5/7/2019Reply

InyoPools Product Specialist

What is the model number of the pump currently on the pool? This may help us determine if your system is compatible with the higher horsepower variable speeds.Matt S.Posted: 5/8/2019Reply

GregPosted: 5/8/2019Reply

InyoPools Product Specialist

In that case, I would go with a similar horsepower variable speed like the PureLine Prime 1.65 HP. The Prime will have enough oomph so that you can run it on lower RPMs for energy savings. If you go with the larger 3-HP variable speeds, there is a danger of cavitation on the higher speeds. So you would basically be paying a bunch of money for speeds you couldn't use.Matt S.Posted: 5/9/2019Reply

BenPosted: 5/7/2019Reply

InyoPools Product Specialist

The variable speed can still be cost-effective, but just not as much as it would be minus the solar panels. The VS gives you the ability to throttle its motor to the minimal RPMs needed to run your panels. Now, the particular speed required to run your specific pool is not something I could calculate off hand. You may have better luck contacting the manufacturer for that.Matt S.Posted: 5/8/2019Reply

Yancy PhillipsPosted: 4/25/2019Reply

InyoPools Product Specialist

Your best pump choice would be the PureLine Prime 2.7 HP Variable Speed Pool Pump - PL2606.Matt S.Posted: 4/26/2019Reply

JerryPosted: 4/25/2019Reply

InyoPools Product Specialist

It sounds like you have a very large commercial pool. The guidelines mentioned in this article may not all apply to you. I suggest you call our support line 407-834-2200 or email upload@inyopools.com to contact our commercial division.Matt S.Posted: 4/29/2019Reply

JaredPosted: 4/24/2019Reply

InyoPools Product Specialist

Did the cleaner only start to malfunction after installing the new pump? Also, what do you mean it is overpowering the cleaner, can you explain what is happening?Matt S.Posted: 4/25/2019Reply

Russell YarboroughPosted: 4/23/2019Reply

InyoPools Product Specialist

Hello Russell - We'd recommend the PureLine Prime model PL2606. The PL2606 is a 2.7 variable speed pump.Robert M.Posted: 4/24/2019Reply

Carl MPosted: 4/23/2019Reply

InyoPools Product Specialist

Ok, have you read the guide above which covers this topic?Matt S.Posted: 4/24/2019Reply

TerinPosted: 4/20/2019Reply

InyoPools Product Specialist

Hello Terin - if you are restricted to 120 volts and 1.5" PVC, you are capped to a 1-1/2 horsepower single speed motors. Dual speed motors above 3/4 HP require 230 volts.A suitable pump would be the Pentair WhisperFlo 1-1/2 HP Energy Efficient.Matt S.Posted: 4/24/2019Reply

Jack B.Posted: 4/17/2019Reply

InyoPools Product Specialist

Hello Jack - We'd recommend a 1.5HP pump and a sand filter that is 19" or larger.Robert M.Posted: 4/17/2019Reply

BobPosted: 3/20/2019Reply

InyoPools Product Specialist

No, it will not.Matt S.Posted: 3/21/2019Reply

KevinPosted: 1/30/2019Reply

InyoPools Product Specialist

Hello Kevin - The goal is to turn the water over once a day. If your pool is 20k gallons, all 20k gallons should run through the filter once a day. In the guide above, steps 1-4 explain how to calculate the water volume of the pool. In step 5 this guide, we have an example of turning over a body of water in 8 hours. The time frame can change but the formula will remain the same.Robert M.Posted: 1/30/2019Reply