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Thread: Backfill on a fiberglass pool......... Gravel or Sand?

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    Join Date
    Aug 2014
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    Canton
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    Exclamation Backfill on a fiberglass pool......... Gravel or Sand?

    I am getting estimates on large fiberglass pools. I have had two builders come out so far and say they backfill with "wet sand". They say that's the only way to backfill all the voids. But most of what I have researched say that sand is not the preferred method anymore as they have found that two things happen with sand. 1. It causes more pressure on the side walls than small gravel 2. If it gets wet, it will settle. Think of a sandcastle on the beach and what happens when the sand gets water on it, it sorta melts down from the shape it was in before it got saturated with water.

    My research on the net says that the preferred method is small gravel because it will lock into place, but if it gets wet, it will not change shape. The gravel also does don't exert the same pressure on the sidewalls as the sand does. So I am throwing this out there to see what experience you have had or what you know first hand as a builder. This pool will be in the 16x40 range in size and with the decking (850 sq ft pavers), fence, electrical, plumbing, filter, pump all included, I'm looking at about 45K to 50K and I don't want to make a big mistake on the install. Thanks!!

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    Join Date
    May 2013
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    North East Ohio
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    953

    Re: Backfill on a fiberglass pool......... Gravel or Sand?

    Gravel gravel gravel gravel gravel

    Here is a small video of my PB during my install...you can see the gravel.

    http://youtu.be/0EkeWaYkNr4
    14,750 GAL IG Fiberglass (16 x 33) NE Ohio || Jandy 1HP 2 speed Pump || Waterco MultiCyclone 16 Centrifugal pre-filter (removed due to not working with sand filter) || 30" 575 Lb. Sand Filter || AquaCal 140K BTU Heat Pump || Solar Cover || Inter-fab Adrenaline Slide || GLI Monsoon Solar Cover Reel || K-2006C Test Kit || BBB with Liquid Chlorine Stenner Injection || Rayner Mighty Mesh Winter Cover

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    Sep 2009
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    Frederick County, MD
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    175

    Re: Backfill on a fiberglass pool......... Gravel or Sand?

    Gravel, that is what my guys used and they were sand folks at one time.
    Jim

    Southern Frederick County, MD - Leisure Moroccan 38 Fiberglass Pool - 19,800 gallons
    Pentair 1.5 hp 2 speed pump - Cartridge filter - Dolphin robot - TF-100 Test Kit - SWCG

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    Join Date
    Apr 2012
    Location
    Newton, NC
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    157

    Re: Backfill on a fiberglass pool......... Gravel or Sand?

    Our PB said he normally used sand for backfill. But, like you, my research indicated that gravel was much better than sand. So, at my insistence (and slightly higher cost) he used gravel for the backfill.
    Vince L

    16' x 37' fiberglass pool, 8' fiberglass spa, Hayward Swimclear C3030 filter, Hayward EcoStar VS pump, Goldline Pro Logic PL-PS-8, Goldline SWCG, Goldline Sense & Dispense pH control, Fiberstars LED's in pool & spa, AquaCal SQ175R heat pump, SR Smith Typhoon slide, Polaris 9300xi robotic cleaner, TF-100 Test Kit

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    laceygirl's Avatar
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    Dec 2013
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    Canberra Australia
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    Re: Backfill on a fiberglass pool......... Gravel or Sand?

    I live in Australia and we have tonnes of fibreglass pools, they're the most common... Gravel is the only way to go... Sand acts like a liquid and can cause some pretty bad cracking....
    Intex Rectangle 18 x 9 x 52', 4544 gallon (18000 litres), 0.75 hp pool pump, 100 sqft Zodiac Titan Cartridge Filter - 40mm, Stenner Peristaltic Pump chlorine injection system, Intex Over The Wall Skimmer, Intex Fittings with 40mm plumbing Lil Patch Of Heaven. Build/Construction http://www.troublefreepool.com/threa...lice-of-heaven

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    Aug 2014
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    Canton
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    Re: Backfill on a fiberglass pool......... Gravel or Sand?

    Thank You all for your responses!! I just don't understand why there are builders still doing it the way "they" want to do it instead of what's better for the pool and the client?? I guess these builders are not interested in a happy client for years to come and that might also get them more business down the road. Too bad there's not a way too weed out these type of builders who use sand!!!!

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