Clay Versus Sand For Pool Base

by Deby
(Wilmington, MA)

Is it better to put a 24' above ground pool on sand or clay? I've heard sand can shift and make divits causing a greater potential for the liner to rip. I also heard it makes it harder to vacuum the pool. Is this true?

Hi Deby. The majority of the pools I install go on a sand base. The sand is used just under the pool liner, not the entire pool. The pool frame needs to sit on solid ground. If the ground in your yard is not stable, or will not pack, you may need to bring in some crushed granite from a sand and gravel yard.

Crushed granite can be used in a couple of different ways. A trench about 18" wide and 6" deep can be dug around the perimeter of your pool. The bottom rail would fall right in the center of this area. The trench gets filled in with the granite and packed solid.

The other way to use granite is to level the entire pool area with it. Granite is so easy to work with and it packs down very nice, a perfect pool base. Sand is then used over top of the granite, just inside the pool frame, as a cushion for the liner.

I have had very little experience with clay but I don't think I would want to put a pool liner on it. I would much prefer sand. Sand is easy to smooth out and it packs down very nicely. Once you have the weight of twelve thousand plus gallons of water it does not go anywhere.

If the sand is properly smoothed out, and the liner properly installed, you will have very few footprints. The only shifting you would ever have would be a cove washing out. If you install a nice dirt cove, before the sand, that should not happen. Keeping dirt packed around the outside of the pool helps also.

Take a look at some of our pool installation pages to see how we work with the sand and how we install liners.

Above Ground Pool Installation

Expandable Liner Installation

Above Ground Oval Installation

Tamp Backfill For Pool

by Brad Harris
(Fairmont, WV)

During the process of digging for our pool, one end was dug about a foot too deep. I have back filled this area with dirt and the ground is now level. My concern is that the back filled area will settle and sink with time.

My question is should I rent a tamper to tamp the back filled area? I'm looking for guidance on how to proceed before I continue with the install. Btw your site is fantastic and very helpful for amateurs like me. It is much appreciated.

Hi Brad. Thanks for the nice words, I'm glad it helps.

It's hard to answer that question not knowing your soil conditions.

In Arizona the ground packs rock hard in a short period of time. Normally a good watering and a few days to dry is all it needs. I then roll my sod cutter over it just to be sure it has packed. The machine is heavy, and if it does not sink the ground is fine.

Without knowing all the details my advice would be the same. Water and let dry a couple of times, and then pack. It will be worth the cost of the rental, if for nothing else than just a little piece of mind.

If you pack it, and it stays level, that sounds like firm ground to build a pool on. The other thing is time, if you are not in a big hurry to install the pool, do some watering and as it dries walk around the area. You should easily get a feeling, underneath your feet, as to how firm the ground is. But the longer is sits, the more it packs, in most cases.

Dug too Deep for Pool

The contractor we hired to dig and level the dirt where our pool is being installed dug too far down. We now have to back fill to get it level. We heard that this is not good and can cause the pool to collapse. If we use a drum roller or plate tamper to compact the dirt again will this be OK to proceed?

Hi. Back filling is not a problem as long as the area is well packed. It's best also to make sure the area is larger than the pool by several feet.

The ground can be leveled, packed, watered and packed some more. It should then be fine for a pool.

Installing An Above Ground Pool Over Sod

by Ken
(Winnipeg, MB, Canada)

I had a contractor install our new above ground pool and they did not cut out the sod. They said they build on top of the existing sod with quarter down stone and fill it in with sand. Is this now going to cause us problems? And now of course the pool sits higher than the 54 inches all around and on the back side it sits 5'5" because of our grade.

Hi Ken. It seems like the biggest problem you have right now is you do not like the looks of your new pool, it sits too high out of the ground. That may, however, be something you will have to get used to.

If the pool is level within a half inch or so and the liner is not full of wrinkles and the base is fairly smooth you probably do not have too much to complain about. That is as long as you OK'd the process of installing the pool over the grass and building up the ground.

The problems I could see in the future might be grass growing through the liner, the sand settling in the stone causing sink holes in the liner, or one side of the pool sinking and becoming out of level.

I have no idea how well the pool was built and if all these concerns were taken into account. It's very possible these concerns were dealt with and you pool will be just fine.

Above Ground Pool Wall Base

by Nick
(Ontario, Canada)

I have prepared and leveled the area to install a 12x24 Aqualeader above ground pool. I am installing the pool myself. The instructions indicate to take material such as rock dust or fine mortar that can conform a solid, permanent base and deposit this material around the rim of the basin. It also indicates the material used should be spread around the perimeter of the pool to a width of 24” and a thickness of 2” and be compacted. This is what the bottom rails and pool wall will sit on. Since the bottom channel of the buttress free support is 2" thick, this will negate any digging of trenches (other than digging for the concrete blocks) for the buttress free supports which the instructions also tell me do to? So this leaves me a little confused. It seems to me that if I did use rock dust around the perimeter then I would also need to fill in the center with the same material so that all would be flush and level, including the straps that run across the pool. Then sand on top of that.
I live in an area with with very hard clay. Would it be okay for me to totally eliminate the use of the stone dust around the perimeter of the pool and place the bottom rails directly on the level ground and dig trenches for the straight side supports and straps to be flush with the ground? Then just add sand?

Thank you for your help!

Hi Nick The ground should be dug out before the stone dust is added leaving it at ground level. You would probably be just fine leveling your ground and using patio blocks under the footplates.

Digging Down to Level is not an Option

by George
(Shakopee, Mn)

I’m planning on buying a 15x26 pool. I have a slop in my yard and finished putting in a retaining wall where I want to put the pool. The wall was back filled with black dirt. Is the weight of the bobcat heavy enough that compacted the ground? Is there a way to measure compaction? On one side of the oval end I might need to raise the ground a little, but there isn’t a retaining wall there to hold the fill in. Can I use dirt and how far do I extend the edge? Or should I use crushed rock for this side? Before I buy the pool I want to ensure my pool will stand.

Hi George

The weight of a bobcat should be enough to pack down the dirt. Soaking with water and using a compactor might help also. A pool ledge should be about 3' beyond the pool for any raised area.