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Thread: A side bonus using foam sheets for pool bottom

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    A side bonus using foam sheets for pool bottom

    I had to install a new liner in my ABG and after looking into it, decided to use foam insulation sheets for the pool floor where I previously had a sand bottom. For my 24' round pool, I needed 15 sheets. I hope I did not mess up here, but all Lowes had in stock was 3/4" so I bought it at $12.24 per sheet. I do not see why it shouldn't be fine - hope so anyway.
    Got to admit i thought it was a real pain to install. The heat and humidity did not help as I was literally drenched in sweat. i just laid out as many full sheets as I could and then cut for the edges.
    To cut the edges, I got a piece of 2x2 (anything would do, this was handy), rounded off one end of it and then drilled holes in a line down the middle of it, sized to fit a pencil.
    Then I just placed the rounded end of the piece of wood against the pool wall with the pencil on the foam sheet, pulled the wood around the wall and it marked the sheet where it needed cut. A few of the pieces did not work out quite that easy, but it went well for the most part.
    Of course before I finished it started pouring down rain. I expected all of the duct tape to be pulled off but it actually held up pretty well.
    I must admit that a few hours into it I was semi-regretting it - but it was just the sweat doing the thinking.
    All done, wall foam up (1st time I have used it also and i have had this pool for about 16 years now), foam cover installed (I have used this before, is the only way to go imo) and I put the liner in the pool.
    The side bonus of the foam floor - adjusting the liner.
    When i had a sand floor, moving the liner around to line it up was not extremely hard, but it did take effort to keep from messing up the sand beneath it.
    With the foam, man what a breeze. the liner just slides around where ever you want it to go. You can stand at one end and barely pull to get a wrinkle out of the other side......
    I am sure i will enjoy it better than the sand bottom when i am done, but just for the ease of installing the liner made it worth it.

    Price was was no more expensive than a pad. My pool has been there for 16 years and I have never had a weed problem, so I just installed the foam over the sand, not worried about nutgrass etc........so a pad would have run me as much......
    I did do all of the installation by myself so if you had 2 people it would be a much easier, quicker job. Well worth it so far, we will see how it holds up

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    linen's Avatar
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    Re: A side bonus using foam sheets for pool bottom

    I definitely agree that foam works great, in my third season here...however I though getting wrinkles out was a little tricky for me since the foam "gripped" the surface of the liner. If I remember right, it was easier to pull the wrinkles out, then push them.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: A side bonus using foam sheets for pool bottom

    interesting the difference. I used the blue Pactiv sheets and it does not grip at all. I ended up not using a shop vac, tho I do admit it may have been a tad faster but I was just a little worried about the vacuum sucking off the duct tape - main reason there was because it had rained so was not 100% confident the tape was still as "sticky" as normal.

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    linen's Avatar
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    Re: A side bonus using foam sheets for pool bottom

    Yeah, it's interesting. Maybe the surface of your foam was wet? Making it more slippery? I used the pink (1.5" thick) extruded polystyrene.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: A side bonus using foam sheets for pool bottom

    no, wasn't wet when I installed the liner. Unfortunately for me it was in the high 90's - I was cooking. I could pretty much stand on one side and pull a wrinkle out from the other side.......I did not use vac and with about 4-5" of water in it, I had a couple of wrinkles and was super easy to push them out.
    Not sure why, but it sure made moving the liner a whole lot easier for me as opposed to the sand

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    Re: A side bonus using foam sheets for pool bottom

    Interesting, I was under the impression that you had to use something like the DOW rigid Highload 40/60/100 etc for compressive strength
    How long have you had the foam boards installed ?
    Any problems ?
    I'm replacing my liner & would love to insulate the hopper bottom
    I'm not sure on the shallow end, seems people walking on the normal rigid foam may "dent" it ?

    Thanks
    Dave
    30 yr old 16x32' IG pool, ~16,600g, Hayward DE 4820 filter w/1.5hp pump, Solar heat

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    Re: A side bonus using foam sheets for pool bottom

    I have only had it installed for a few weeks. Nothing personal, but I sure hope u are wrong - I really do not want to have to drain the pool etc.....

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    linen's Avatar
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    Re: A side bonus using foam sheets for pool bottom

    I'm on my third season and the only place I have issues is under my "wedding" cake steps. They are not symmetric on the bottom and one side puts more pressure on the floor than the other side, causing a slight depression in the foam. No other significant dents.

    The extruded (not expanded) polystyrene foam is fine.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    linen's Avatar
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    Re: A side bonus using foam sheets for pool bottom

    Quote Originally Posted by donberry
    no, wasn't wet when I installed the liner. Unfortunately for me it was in the high 90's - I was cooking. I could pretty much stand on one side and pull a wrinkle out from the other side.......I did not use vac and with about 4-5" of water in it, I had a couple of wrinkles and was super easy to push them out.
    Not sure why, but it sure made moving the liner a whole lot easier for me as opposed to the sand
    That may be the difference, I installed in the fall and my water stayed cold as I filled.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: A side bonus using foam sheets for pool bottom

    I looked at the Owens Corning Foamular at HD, its good for 25 psi
    At 8' depth there is approx 18.2 psi, so looks like it will work
    Only other thing someone mentioned (somewhere) is the possibility of someone "denting" the foam
    They mentioned it will not rebound from a dent.....not that I think that is a huge concern
    30 yr old 16x32' IG pool, ~16,600g, Hayward DE 4820 filter w/1.5hp pump, Solar heat

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    Re: A side bonus using foam sheets for pool bottom

    I do have one problem. There are a couple of places now where it seems the foam must have moved a little as the liner is recessed between the sheets. It had rained before I put the liner in and when installing the liner, maybe the foam moved a little ?
    There is maybe a little less than a 1/4 "crack" in a couple of places. One is maybe a foot long, the other is maybe 2 feet. I am not worried about the liner ripping there as it has just stretched down to fill the crack. Is small enough you do not notice it when walking over it unless u deliberately stick a toe in it, but of course that is where all of the dirt accumulates.
    Not a huge deal as I run a Polaris 65 and it keeps it clean. I do not think anyone else even noticed until I pointed it out, but as the "installer", of course it bugs the heck out of me.
    The foam has been a huge hit with the family. They really like it. I am guessing with the weight of the water, the foam is so compressed it would take quite a bit to leave an impression in it. Will obviously know more next year after it has been up a while

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    Re: A side bonus using foam sheets for pool bottom

    If I'm reading the right data sheet the rigid you bought only has a compressive strength of maybe 9psi
    So at 4' water depth over 16 psi, so the product crushes
    Maybe not a problem with an ABG pool ?
    But with an IG pool you do not want to have the liner stretch an extra 1"

    Looking at the 25 psi Owens Foamular its $10 for a 2x4 sheet for 1" = R5
    I'd prefer the 4x8 sheets but it is tongue & groove
    They only list the 2" available in 4x8, 1" might be special order - rather not
    I'm interested in mainly keeping the pool warmer, keep the water away from the heat sucking cold cement
    We have a stream on the property & high water table, so the pool stays cold without solar heat

    How deep is the crack ?
    That will tell you how much the 3/4" insulation compressed
    From the IG liner info it seems stretching up to 1" is not a problem
    I know what you mean about "knowing" about the problem as the installer, one of the pains of DIY
    30 yr old 16x32' IG pool, ~16,600g, Hayward DE 4820 filter w/1.5hp pump, Solar heat

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    Re: A side bonus using foam sheets for pool bottom

    the crack is not from the foam compressing, but apparently the rain weakened the duct tape enough so that when i was putting in the liner, adjusting it, pulling it around etc, where the foam boards met and were taped together must have pulled apart ever so slightly. I never even noticed it until I saw some dirt accumulated in it as I had not run the polaris yet that day. I am guessing that it was there at some point when I was filling the pool so basically the liner just "adjusted" itself to fill in that area, so the liner may not really have actually stretched anymore than usual. It would be different if it just suddenly "collapsed" after it had already been filled and the top edges on, not giving the liner any "give"....
    Nothing i can really do about it now. No way I am draining the pool to fix that small of an area. I wish it wasn't there, but unless the cleaner hasn't been run and there is dirt in it, u honestly never notice it. i only noticed it as there was a perfectly straight line of dirt....
    I could be wrong and often am, but I would think that if the foam was going to crush from the weight of the water, it would have done so by now. I have a severe back problem and do not bend at all so when i was installing the foam, I was crawling around on it on my hands and knees the entire time. It would leave some small indentations where my knees were if I was in the same spot for a bit, but when I moved, within minutes the indentations disappeared. At the time i was thinking once the weight of the water was on it, it would take away that extra bit of "compression" room and so far it seems as tho it has.
    Obviously the biggest thing will be long term use.

    If I were doing it again, at this point I would still use the same foam. the only thing different i would have done is after it had rained, i should have pulled up all of the duct tape that had lifted and put down all new instead of pressing it back down and taping over the "old".
    But to be honest, at that point my knees were killing me and I just wanted it done.
    I now regret it because it would have been just about perfect (so far) instead of having those 2 "cracks" in it.

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