First Pool foundation question

otherguy

Member
Feb 24, 2021
5
MO
We just ordered an Intex Ultra XTR 18x52 round pool.
We are going to have someone come out and level a 20ft square area to put the pool in, they will also be brining sand to put on top of the dirt.

My first two question of many probably.
  1. Do I need to add foam on top of the sand and then something like Gorilla Pad or can I just do Gorilla Pad?
  2. With this pool do I need something harder under the legs/post of the pool?

I wasn't sure what the purpose of foam on top of sand would be. We are planning on leaving this pool up all year round even though Intex says to take it down, we don't want that hassle if we can avoid it.
Thanks for any suggestions.
 

Mdragger88

Bronze Supporter
Jun 1, 2018
1,946
Hernando, Ms
Pool Size
26000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
1. Gorilla or other pad is optional- the idea is the smoothest bottom free of protruding rocks as a filled pool is alot of weight
So sand + gorilla pad (or other types of padding like insulation sheets) helps insure this.
2. Pavers sunken down to where the tops are level with the pool bottom otherwise the legs will/can sink into the ground causing an unlevel pool when filled w/ water.
Some people use wood but pavers are obviously less prone to rot.
 

kellyfair

Gold Supporter
Bronze Supporter
Jun 29, 2016
4,248
Tampa, FL
Pool Size
7000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
I used tarp then gorilla pad with my Intex. Pad was just to keep anything from puncturing - it’s too thin to provide any cushion. I didn’t do sand under the Intex. Our soil is super sandy so we just leveled and installed.
 
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otherguy

Member
Feb 24, 2021
5
MO
I have been reading about others only using the foam on the ground, not doing the sand because there are concerns about sand washing away.
So is sand really needed or does it serve any purpose?
 

Mdragger88

Bronze Supporter
Jun 1, 2018
1,946
Hernando, Ms
Pool Size
26000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
Just more cushion. In a regular above ground you have to think about how they made the liner & what clearances are expected but with an intex its a preference especially if u don’t have rocky ground.
 

BowserWowser

Well-known member
Feb 28, 2021
52
Virginia Beach, VA
Surface
Vinyl
We're doing a permanent AGP, not an Intex, but my installer said he won't put down a Gorilla pad or anything under the liner because it's not thick enough to make a difference and increases the chances of wrinkles. They are doing sand, though, and an industrial herbicide to prevent nutgrass.

That said, I live close to the coast, so our ground isn't very rocky.

I considered some kind of foam under the liner, but then I stopped and thought about the last time I was in a pool and thought the bottom was too hard and uncomfortable. The answer for me: I've never thought that! So I'm skipping the foam :p
 

otherguy

Member
Feb 24, 2021
5
MO
So far we are going to do the sand and the 1" XPS foam taped together and then gorilla pad on top of that. I have seen lots of people on here do the foam + gorilla pad but wont do sand in fear of it washing away, but I have seen others do all three with no issues. :unsure:

I might be a little worried about the sand eroding away when it rains but guess we can see how it goes.
 

kellyfair

Gold Supporter
Bronze Supporter
Jun 29, 2016
4,248
Tampa, FL
Pool Size
7000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
So far we are going to do the sand and the 1" XPS foam taped together and then gorilla pad on top of that. I have seen lots of people on here do the foam + gorilla pad but wont do sand in fear of it washing away, but I have seen others do all three with no issues. :unsure:

I might be a little worried about the sand eroding away when it rains but guess we can see how it goes.
It’s ok to use a thin layer of sand under the Intex. Just don’t do more than an inch or two. Oh wait... foam too? I wouldn’t bother with much sand, unless you are concerned about rocks working their way through.
 
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otherguy

Member
Feb 24, 2021
5
MO
I finally got our pool today and was browsing through the instructions and saw where Intex specifically says not to put sand under the pool. One thing to use a thin layer but I was assuming people were using 2" or more and surprised that it seems like lots of people use sand when Intex says not to.

So confusing, lol.

We plan on keeping this up all year round so I want to do what's best. All I know at this point is we will use the 1" foam.
I think I will put the tarp/barrier that came with the pool down first, then the foam. Still undecided on the sand unless a thin layer, but I will need to tell the guys that are doing the excavating so they know how much to bring, if any.
 
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kellyfair

Gold Supporter
Bronze Supporter
Jun 29, 2016
4,248
Tampa, FL
Pool Size
7000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
I finally got our pool today and was browsing through the instructions and saw where Intex specifically says not to put sand under the pool. One thing to use a thin layer but I was assuming people were using 2" or more and surprised that it seems like lots of people use sand when Intex says not to.

So confusing, lol.

We plan on keeping this up all year round so I want to do what's best. All I know at this point is we will use the 1" foam.
I think I will put the tarp/barrier that came with the pool down first, then the foam. Still undecided on the sand unless a thin layer, but I will need to tell the guys that are doing the excavating so they know how much to bring, if any.
Precisely. Unless you have really rocky foundation, you’ll be fine with just foam. I only had tarp and thin gorilla pad under mine.
 

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BowserWowser

Well-known member
Feb 28, 2021
52
Virginia Beach, VA
Surface
Vinyl
I'm about the farthest thing from an expert, but just common sense tells me the foam would essentially be serving the same purpose as the sand, so you don't need both.

My biggest concern with sand is the potential for moles to dig into it. Sure not a problem with foam!
 
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otherguy

Member
Feb 24, 2021
5
MO
Thanks for all the replies. So that I can save my sanity (and quit researching this part) I am just going to.......
get the ground leveled
put down the tarp that came with the pool
put down foam and tape the seams
then put gorilla pad on top of that to help with hiding the seams and such
I will put pavers under the feet, plan to cut away the foam and the pavers will rest directly on the tarp/ground.
the part of excavation and tarp that is still exposed we are going to cover the area with mulch or small garden rocks.

Just going to go with that and call it good, that way I can start researching chemicals and such.
 
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splashpad

Bronze Supporter
Aug 2, 2017
2,712
SE Kansas!
Thanks for all the replies. So that I can save my sanity (and quit researching this part) I am just going to.......
get the ground leveled
put down the tarp that came with the pool
put down foam and tape the seams
then put gorilla pad on top of that to help with hiding the seams and such
I will put pavers under the feet, plan to cut away the foam and the pavers will rest directly on the tarp/ground.
the part of excavation and tarp that is still exposed we are going to cover the area with mulch or small garden rocks.

Just going to go with that and call it good, that way I can start researching chemicals and such.
We definitely wish we had something over the sand in our pool, as pushing off causes small divots, but otherwise we do like having the "softer" cushion under our feet (funny how it bothers some but not others, I think pool depth has a LOT to do with that)

I think that sounds like a good workable plan!

  • As for chemicals, they are simple for us in the midwest!
  • Get a GOOD test kit! Test strips won't lower your pool care costs! ;)
    • Chlorine (added frequently)
    • a little CYA/Stabilizer (added only at opening, tested after large water loss/refill)
    • then the rest depends on whether you have hard or soft water and how often you drain/lose water :) (personally: we also add salt for comfort, but keep the level low)
    • If you haven't already, Pool School > Pool Care Basics - Trouble Free Pool
Can't wait to see pics of the new pool up and splashing! Hey, any chance of sunshine?? lol!!