Making the Pool Round

We are in the process of setting up a used 18' round pool. We put down landscaping blocks to set the ring on and put up the side walls, but we're having problems getting it perfectly round.

When we measure across one way it will be 18' 1 1/2" another way will be 17' 10" & so on. We've been trying to slide it around to make it even but are having a hard time getting it just right. How important is it to have it perfectly round?


Hi. There are two really important things to remember about building an above ground pool. They must be perfectly level and perfectly round.

The best way to make a pool round is to work off a center point and use the radius measurement. I always do this before the wall is installed. Actually, I take a tape measure around with me as I am connecting the bottom rails and set them all at the 9' mark, for an 18' pool.

making above ground pool round

All 18' pools will not have a radius of 9' exact. Some may be 9' 1" while others are 8' 11". It makes no difference what the radius is as long at it is the same all the way around. You need to keep working it until it is.

This same method can be used for a pool where the wall has been installed. Use a center point on the inside of the pool and work a tape measure around the bottom rails. Once the pool rails are round double check the bottom rail gaps and make sure they are all the same.

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Putting Round Pool Into Oval Barrier

by Teri

I got talked into purchasing something different than what I wanted. I BOUGHT an 18' round above ground. I wanted to place it into the in ground oval pool area that has been filled with sand.

It appears that the larger pool I got talked into is about 1' bigger than the pool sides for the in ground filled with sand where I wanted to place the above ground pool. Can I put a round above ground into an oval area without issues?

Will the round pool adjust to the sides being held by the in ground pool lip or will it cause issues?

Hi Teri. What you are talking about doing will cause you nothing but problems. None of the pieces will fit correctly. An 18' above ground pool needs to be perfectly round and perfectly level, there are no exceptions.

Installing a pool on sand is also not recommended. The pool should be set up on solid level dirt.

From what I understand your options might be to find a new location for the pool, or to remove the sand in your ideal location and to fill it up with dirt. When filling it up you could fill it to the top so that the new pool can expand out to its intended dimensions.

Comments for Putting Round Pool Into Oval Barrier

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Aug 07, 2011
by: Teri

Thanks for your answer... that's what I was afraid of. :-)

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Pool Wall Bowing Out on New Round Pool

by Mary F
(Cincinnati Ohio)

Pool Wall Bowing Out

Pool Wall Bowing Out

We just finished installing a new 24’ x 54” Wilbar Ventura above ground pool. It is installed on a site where there was an existing pool of the same size. We worked diligently to get the details perfect. Redoing some steps to ensure perfect level and perfect round. Everything looked great until the water level got to around 3/4 of the way full, approximately 10” below the skimmer.

We noticed one area of the wall is bowed/bulging out. It is near where the stainless service panel is joined. I hope you can see from the pictures that it is pushing out on the upright. Any insight on what’s causing this would be so helpful.

We did stop adding water and started pumping it out to alleviate the pressure until we fix the issue.

Hi Mary My guess is the bottom rail is pushed in a little at this one footplate. If it were pulled out to make the pool round the wall would straighten out.

The most common cause of this is the wall not meeting properly at the nuts and bolts. It is important that the distance needed to align the wall bolts be divided equally between many footplates. I have had to take the wall completely out and re gap all of the bottom rails in order to make the wall meet at the end and also to keep the pool round.

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Pool Out of Round

My husband and his friends have set up our pool walls for the second time and it is out of round. He refuses to research himself or follow my researched instructions. The 27' round is level but out of round. Liner is not installed. Is there a way to adjust the tracks for roundness with the wall up?


The pool does need to be round, you are correct on that. Before taking the wall down again I would check it closely.

You need to find your center point and measure out 13' 6". It may take a bit of searching to find the exact center point but worth the time. Once you have a good center see how close the pool is to round. A little off in a few places can probably be corrected with the wall up. If it is too far off I would start over.

Don't use the tape measure across the pool method. It may tell you the pool is not round but does not much in telling you how to correct it. Use the radius method.

The other thing to consider is your bottom rail gap. That gap needs to be uniform, the same on every footplate. Making the pool round can change this gap if you are not careful so keep an eye on that.

Perfectly round and perfectly level before you install the liner, that's the best way to go.

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