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Thread: Vermiculite question

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    Vermiculite question

    Hi Guys, im new to this forum and wanted to say thanks to everyone. I recently took on the task of installing my own pool and this site has helped me greatly! I have run into a problem im hoping i can get some feedback on....

    My pool excavator over dug my pool a good bit. My corners were basically hanging over air and I have some of my walls up on blocks. I poured concrete under the corners so thats good now and I'm going to pour gravel on the bottom to fill up the overdig and Vermiculite over that. One thing im wondering about is whether vermiculite will bond to concrete. I know you cant bond concrete to concrete withut a primer but can you do it with Vermiculite to concrete?

    Also on my walls, they are dug out about 1 ft too much on either side. I can either try to build the walls up with concrete and vermiculite over that or just leave them as they are and let my liner stretch to fill it. I know this may shorten my liner life by a year or two but I already ordered the liner and have it. The company I ordered my kit from said that the liner will actually stretch to fill in this overdig and to just order a correct fitting liner next time. I hope I explaned that correct......

    Basically my liner is designed for a hopper thats 10x6 but my walls are more like 12x6 with the overdig.

    Thanks guys
    18x36 Kafco steel wall Vinyl liner pool.21,000 Gallons 8ft deep. Pentair 420 cartridge filter, Intelliflow pump, Pentair IC40 salt water generator with Easytouch control system. 2 skimmers, 2 returns

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    Re: Vermiculite question

    I don't see how they could bond, but I'm not 100% sure. When the installer put our verm. floor, it's a hard packed sand. It cures somewhat, but it didn't get hard like concrete does.
    20k gal pool/spa, marc, Intellichlor SWG, 2 hp pentair whisperflo, Pentair clean & clear filter, Raypack Reheem 266 heater. Taylor K2005 test kit.

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    Re: Vermiculite question

    ive never seen vermiculite before so maybe "bond" isnt a good term....I guess i just want to know if its ok to put vermiculite on top of the concrete and will it stick to concrete. Thanks
    18x36 Kafco steel wall Vinyl liner pool.21,000 Gallons 8ft deep. Pentair 420 cartridge filter, Intelliflow pump, Pentair IC40 salt water generator with Easytouch control system. 2 skimmers, 2 returns

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    JasonLion's Avatar
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    Re: Vermiculite question

    If I am following correctly, the vermiculite should be fine even if it doesn't develop a true bond. You are basically putting the vermiculite into a bowl, so there isn't any where it could go even if it doesn't fully bond.

    Liners will stretch quite a bit, but stretching them that much often leads to minor problems latter on. I would fill things in at least part way if that is at all practical.
    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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    Re: Vermiculite question

    I cant think of a way to fill the side walls in that well. They are basically at a 3ft slope instead of a 4ft slope. any ideas? if i concrete the walls will it still be ok to put vermiculite on top of it then? Thanks for your help guys
    18x36 Kafco steel wall Vinyl liner pool.21,000 Gallons 8ft deep. Pentair 420 cartridge filter, Intelliflow pump, Pentair IC40 salt water generator with Easytouch control system. 2 skimmers, 2 returns

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    Join Date
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    Re: Vermiculite question

    I think it would be ok to put vermiculite on concrete. It will stay in place long enough to get your liner in and filled up with water. You could also mix some portland with the excavated fill dirt and build your wall out instead of using concrete.
    35K IG Vinyl 20 x 40 self built pool, Hayward Pro Series High-Rate Sand Filter 31" 98gal/min, Hayward TriStar 1.85hp, Hayward 400btu heater, BBB method w/Hypo, Jazz light w/matching fiber optic rope lighting around coping w/syncronized color wheels. Concrete Paver deck.

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    Join Date
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    Re: Vermiculite question

    Hey all.

    bb2, welcome to TFP!!

    Vermiculite doesn't 'bond' to anything. As Jason pointed out, it fits into the 'bowl' of you pool. If you leave voids or places where the substructure (dirt, sand, gravel, etc.) washes out, the vermiculite will crumble and drop into the void

    bb2, even though you're getting your verm for $12/ bag, that's a lot of mixes to make up the difference in your wall, and, you add 1/2 bag of cement to each bag @ ~ $8/ bag, so you're talking $16 per mix and you'll need at least 20 extra mixes to fill that void

    I'd suggest filling the voids as best you can with #57 stone, you won't be able to completely fill them to within 2" of the finished floor, but it should get you closer and save you $. You can go with concrete or sand and cement to fill the voids, but gravel lets water flow beneath the verm - water passing through the verm will wash out the cement, after a while, and leave you with 'mushy' areas. If you have any bad/ unworkable mixes of the vermiculite, use that material to fill the voids.

    You might be able to 'cheat' the slopes ~ 1" on both sides and still have a viable liner, but I wouldn't go any further! My best advice is to fill the sides to match what the liner was cut to.

    p.s. if you haven't seen it, there's a series on DIY IG liner pools in the "Further Reading" section of "Pool School"
    Luv& Luk
    -Ted

    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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