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Thread: Main Drain - (2) 8" or channel drain??

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    Main Drain - (2) 8" or channel drain??

    Anyone have an opinion which is better for a main drain in a gunite new build? Looks like PB is going to put channel in as spa drain too!
    Any thoughts? Thanks
    IG gunite Edmond, OK(OKC), 18x36 freeform ~20K, 4-8' deep, Pentair equip, (2) 3hp VS+ pump, 520 cart filter, 3 LED, Easytouch8, ItellichlorIC40 SWG, Polaris 3900 cleaner, Spa 8'x18"raised, 20' raised bond beam 2 sheers, Stonescape Tahoe Blue quartz plaster, TF-100 kit.
    Feb. 25, 2014 dig started, May 24, 2014 filled.

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    JasonLion's Avatar
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    Re: Main Drain - (2) 8" or channel drain??

    Either way. This is more of an esthetic choice than a practical difference.
    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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    mas985's Avatar
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    Re: Main Drain - (2) 8" or channel drain??

    Or you could just skip it for the pool. It really isn't necessary and sometimes causes more problems than what it is worth.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Main Drain - (2) 8" or channel drain??

    Thanks for the info! Since our contract says 8" drains, I was a little surprised when the channel ones were left on the job.
    Makes me leery of what else will be different. Skip the main drains? And go with wall mounts or skimmer supply only??
    IG gunite Edmond, OK(OKC), 18x36 freeform ~20K, 4-8' deep, Pentair equip, (2) 3hp VS+ pump, 520 cart filter, 3 LED, Easytouch8, ItellichlorIC40 SWG, Polaris 3900 cleaner, Spa 8'x18"raised, 20' raised bond beam 2 sheers, Stonescape Tahoe Blue quartz plaster, TF-100 kit.
    Feb. 25, 2014 dig started, May 24, 2014 filled.

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    mrcarcrazy's Avatar
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    Re: Main Drain - (2) 8" or channel drain??

    That's a decision only you can decide. Personally I think a main drain is beneficial. Of course everything has pros and cons.

    If you are pulling from the deep end and from the skimmers you are going to have less "dead spots". (in my head at least)

    If you ever need/want to drain the pool, that's much easier to do with a main drain. (no rental equipment needed)

    My Suggestion is to ask the PB every question you come up with. This at least lets him know you are watching, and you aren't a complete moron. I bug the heck out of my PB with every question I come up with. He doesn't mind it, and it lets him know that I am anal retentive. So if he's not sure what we want, he asks for clarification instead of just jumping in head first.

    Apparently most homeowners don't ask many questions, they just go with the flow and only care about what color the tile is.
    IG gunite/plaster pool/spa Started 1/17/14, Plastered 5/16/14
    Size: 12'-21'x39' free form, depth ranging from 4' to 7, attached 6 person spa with spillover.
    Equipment: Whisperflo 2hp pump, Pentair 30" sand filter, Pentair Mastertemp 400k BTU heater, 1hp Whisperflo for waterfalls, and a blower for spa floor

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    mas985's Avatar
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    Re: Main Drain - (2) 8" or channel drain??

    The whole circulation thing with main drains is a bit of a myth. There are many other plumbing designs that actually work better for circulation that do not include main drains. In fact, a simple lower return or one pointed downward is far more effective at circulation than is a main drain. Returns have a higher exit velocity and therefore are better at mixing and circulating the water.

    Here is an interesting study that you might be interested in:

    http://www.poolinspections.com/manua...out-drains.pdf

    Along with a video: http://www.youtube.com/watch?v=0IOUGhuKkSM

    Also, skimmers tend to work better without a main drain since the flow rate is higher than with the main drain (i.e. diverted flow). So it can allow you to run a pump at lower speeds for the same effectiveness in skimming which will save in energy costs. In many parts of the country, building residential pools without main drains is beginning to become the standard.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    mrcarcrazy's Avatar
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    Re: Main Drain - (2) 8" or channel drain??

    I do find that interesting. It doesn't change my thoughts that more drains and more returns is good for circulation. I do agree that returns are more important since they are under positive pressure. I'm actually shocked at the results of that video. I want to blame it on the large surface area of the drain. But even then it supports the article linked.

    This doesn't change my stance that each owner should make their own mind as to what they want. As there are pros and cons to each method.

    -With a drain you have more options. Options are never bad.

    -With a drain you have more pipe to potentially leak. Leaks are always bad. main drain leaks are especially bad.

    I'm no expert....but in my little world I'm right. You'll never convince me otherwise. (disclaimer)
    IG gunite/plaster pool/spa Started 1/17/14, Plastered 5/16/14
    Size: 12'-21'x39' free form, depth ranging from 4' to 7, attached 6 person spa with spillover.
    Equipment: Whisperflo 2hp pump, Pentair 30" sand filter, Pentair Mastertemp 400k BTU heater, 1hp Whisperflo for waterfalls, and a blower for spa floor

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    Re: Main Drain - (2) 8" or channel drain??

    Thanks guys for the info and thoughts!!
    Right now I'm just excited my PB plumbed the spa with rigid sched 40 PVC, unheard of in OKC and as per the contract!! Maybe a new trend in this area!! Looking forward to pressure test…...
    IG gunite Edmond, OK(OKC), 18x36 freeform ~20K, 4-8' deep, Pentair equip, (2) 3hp VS+ pump, 520 cart filter, 3 LED, Easytouch8, ItellichlorIC40 SWG, Polaris 3900 cleaner, Spa 8'x18"raised, 20' raised bond beam 2 sheers, Stonescape Tahoe Blue quartz plaster, TF-100 kit.
    Feb. 25, 2014 dig started, May 24, 2014 filled.

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