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Thread: Advice Needed on Sand to vermiculite bottom

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    Advice Needed on Sand to vermiculite bottom

    I recently bought a house with a 15 year old inground pool in need of a new liner. We believe the bottom of the pool is sand but we are not sure. The contractor has suggested putting a 2" layer of a vermiculite-cement mix on top of the sand bottom to improve durability and insulation for an additional cost of $1,600. I am not convinved this is necessary or worth the additional cost. The pool is still in excellent condition, we never detected any foot prints or other problems on the bottom of the pool. It seems the liner simply wore out after a good long life. Any thoughts on the utility of putting vermiculite over sand or the benefits of such added insulation would be GREATLY appreciated.

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Advice Needed on Sand to vermiculite bottom

    Welcome to TFP!

    Sand requires a little more care during liner replacement, but otherwise the end result in nearly identical. I would stick with sand.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Join Date
    Mar 2007
    Coastalish 'down easter'

    Re: Advice Needed on Sand to vermiculite bottom

    Welcome to TFP!!

    Sand is a fine base for a liner pool. If you replace the liner, you'll need to reposition some of it, re-trowel it and probably have to replace some that has washed away over the years. (here is a link to my assessment of liner bottoms)

    While I prefer vermiculite, you'd save ~ $1550 if you stay with sand (then again, if the price of $1600 included the cost of the vermiculite and cement and troweling it- that's an INCREDIBLE deal! )

    Please keep us informed as to your decision and, if you can, take pics of the process
    Luv& Luk

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

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    Re: Advice Needed on Sand to vermiculite bottom

    Thank you all for the speedy and informative replies! I am relieved not to need to spend the $1,600 since sand , while not optimal, seems to be a pretty reliable base. Vermiculite was recommended predominantly for its insulating effects, which interestingly, neither of you said was a major plus over sand. The original liner is black which I was told was put in to attract heat. Living in chilly Vermont, getting the most out of a pool requires attracting and retaining as much heat as possible. However, putting in a new black liner I was told would be costly and that I would have to sign a waiver due to the dangers of poor depth perception in pools with black liners. I opted for a dark blue liner instead. The contractor recommended the vermiculite as one option for helping retain heat as well as using solar rings to attract heat....all the reviews I found on solar rings were NEGATIVE.
    Unfortunately, neither of the recommendations seem to be worth the investment. At this point it looks like I will just go with the dark blue liner and a solar cover and hope global warming does the rest to heat my pool! Thank you again for all your advice and I welcome any additional thoughts!

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    Re: Advice Needed on Sand to vermiculite bottom

    Oh, I should be able to take pics of the process and report back as to the success of the operation! Many many thanks for all the advice!

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    dmanb2b's Avatar
    Join Date
    Apr 2009

    Re: Advice Needed on Sand to vermiculite bottom

    Welcome to TFP Skip the'll love the dark blue liner. Get a solar cover to retain heat overnight...yes it's a nuisance, but it sure is nice to have a warm pool
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

    Pool School, TFTestKits, Pool Calculator

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    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: Advice Needed on Sand to vermiculite bottom

    On the subject of retaining heat and since you seem already committed to a solar cover, consider solar heat.

    Probably in that $1500 ballpark and you would get a significant increase in the warmth of your pool.

    (and, yes, by not mentioning it, the posters above are saying the insulating effect of vermiculite is very, very minor....certainly not worth the cost)
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Advice Needed on Sand to vermiculite bottom

    It is GOOD to know the solar panels work, thank you! If the pool is too chilly this summer I will explore that option. Another pool company mentioned solar heat but I have not yet researched it. I have to first get past my concerns over the aesthetic impact of many feet of solar panels in my backyard on top of the investment! I bought the solar cover last summer so that is a sunk cost in this equation. I bought it after being (mis)lead to believe that it actually attracts heat and transfers it to the water (I have an opaque not a clear one) rather than just retaining it...hence, I am trying to do more homework this year...Thanks for the insights and recommendations - it is saving me lots of money and headaches!

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