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Thread: Main Drain Question

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    Main Drain Question

    This forum is getting better every day.

    I have a question about my main drain. It is plumbed up to my skimmer instead of directly to the pump. The pool is an IG fiberglass and my best guess is that it was built about 25 years ago. Will a drain set up like this still get some flow due to siphoning action when the pump is running? I've tried brushing small debris towards the drain and I don't ever see anything move into it. I know it's not plugged because water will siphon into the skimmer if I block the opening and let the pump take out the water in the skimmer below the pool water line. Is this a normal configuration for a main drain?
    20K IG Fiberglass, 3/4 hp Sand, Hayward ColorLogic

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    Yes for the flow answer but it is obviously a bit more difficult to modify your flow with your setup. Yours is probably a "normal" setup but not ideal. Several pool builders I interviewed looked at me like I was crazy for asking for each skimmer and main drain to be plumbed separately back to the equip pad. Finally I found a builder that did this as their standard and I knew I had a good company.

    Check to see if you take out your skimmer baskets if the opening to the suction pipe is threaded. Meaning you could put a threaded cover or threaded reducer if needed to adjust the pipe size and/or flow at the skimmer. That would be one way to boost flow at the main drain. I have valves at the equip pad to adjust flow but this might be an option for you. Just beware that you will be effecting the psi of your system by restricting the flow. This is generally not a problem if you pipe size is on the larger side.

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    Re: Main Drain Question

    Quote Originally Posted by nocaster
    Is this a normal configuration for a main drain?
    Normal? Frequently. Correct? No!!

    You can purchase a balancer that will solve your issue. It's a clever device that "sucks" down to the bottom of the skimmer, under the basket, and will pull water from the main drain. While it's quite simple, you literally have to hold it in your hands to understand how it works. I have Sta-rate skimmers and the sta-rite number on this balancer is 8650-39. Mine has been trouble free for three years. Probably less than twenty bucks.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Interesting as my main drain is plumbed the exact same way. How would you tell if the flow is set properly?

    thanks,
    15,500 gal, inground gunite pool with 7 ft spa, 2 speed pump 2hp/.33hp, 3/4 hp booster pump, Intermatic P1353 timer, AutoPilot SC-48, Sand filter with ZeoBest, Heater, that I never use . . .

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    Re: Main Drain Question

    Quote Originally Posted by duraleigh
    Quote Originally Posted by nocaster
    Is this a normal configuration for a main drain?
    Normal? Frequently. Correct? No!!

    You can purchase a balancer that will solve your issue. It's a clever device that "sucks" down to the bottom of the skimmer, under the basket, and will pull water from the main drain. While it's quite simple, you literally have to hold it in your hands to understand how it works. I have Sta-rate skimmers and the sta-rite number on this balancer is 8650-39. Mine has been trouble free for three years. Probably less than twenty bucks.
    I'm pretty sure my skimmer is a Sta-Rite. The drain hole is just above the basket and the opening is towards the pool wall. I'm googling that part number but not finding anything.
    20K IG Fiberglass, 3/4 hp Sand, Hayward ColorLogic

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    Quote Originally Posted by lovingHDTV
    Interesting as my main drain is plumbed the exact same way. How would you tell if the flow is set properly?

    thanks,
    After looking online I think I may have one of these things. In my case it is a flow check valve thing where the flow through the valve is controled by closing the hole. I never knew what this thing was so I just pulled it out of the skimmer.

    Mine looks like item #3 if that helps anyone:
    http://www.poolcenter.com/parts_skimmer ... kimmer.htm

    How would you adjust this thing? Is there a recommened amount of flow from the main vs the skimmer?

    thanks,
    15,500 gal, inground gunite pool with 7 ft spa, 2 speed pump 2hp/.33hp, 3/4 hp booster pump, Intermatic P1353 timer, AutoPilot SC-48, Sand filter with ZeoBest, Heater, that I never use . . .

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    Quote Originally Posted by lovingHDTV
    Quote Originally Posted by lovingHDTV
    Interesting as my main drain is plumbed the exact same way. How would you tell if the flow is set properly?

    thanks,
    After looking online I think I may have one of these things. In my case it is a flow check valve thing where the flow through the valve is controled by closing the hole. I never knew what this thing was so I just pulled it out of the skimmer.

    Mine looks like item #3 if that helps anyone:
    http://www.poolcenter.com/parts_skimmer ... kimmer.htm

    How would you adjust this thing? Is there a recommened amount of flow from the main vs the skimmer?

    thanks,
    Does your drain line connect to the plumbing underneath the skimmer? Mine is actually connected to the skimmer above the basket. I could see how reducing the flow from the skimmer would pull more from the drain if they connect under the skimmer.

    A side view would look something like this:
    Code:
    Top of Skimmer
    
    |             |
     |           |________
     |            ________  To Drain
     |Basket |
     |           |
      \_      _/
          |  |
          |  |
          |  | 
          |  | To Pump
    er....my ASCii art is not rendering correctly.
    20K IG Fiberglass, 3/4 hp Sand, Hayward ColorLogic

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    http://www.poolcenter.com/parts_skimmer ... kimmer.htm

    Yeah, that's it. It has to be skimmer specific (sta-rite makes several). You just adjust the "restrictor plate" 'til you get the desired flow from both units.....be it two skimmers or a skimmer and main drain.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Quote Originally Posted by nocaster
    Quote Originally Posted by lovingHDTV
    Quote Originally Posted by lovingHDTV
    Interesting as my main drain is plumbed the exact same way. How would you tell if the flow is set properly?

    thanks,
    After looking online I think I may have one of these things. In my case it is a flow check valve thing where the flow through the valve is controled by closing the hole. I never knew what this thing was so I just pulled it out of the skimmer.

    Mine looks like item #3 if that helps anyone:
    http://www.poolcenter.com/parts_skimmer ... kimmer.htm

    How would you adjust this thing? Is there a recommened amount of flow from the main vs the skimmer?

    thanks,
    Does your drain line connect to the plumbing underneath the skimmer? Mine is actually connected to the skimmer above the basket. I could see how reducing the flow from the skimmer would pull more from the drain if they connect under the skimmer.

    A side view would look something like this:
    Code:
    Top of Skimmer
    
    |             |
     |           |________
     |            ________  To Drain
     |Basket |
     |           |
      \_      _/
          |  |
          |  |
          |  | 
          |  | To Pump
    er....my ASCii art is not rendering correctly.
    Yes my drain connection is below the skimmer.
    15,500 gal, inground gunite pool with 7 ft spa, 2 speed pump 2hp/.33hp, 3/4 hp booster pump, Intermatic P1353 timer, AutoPilot SC-48, Sand filter with ZeoBest, Heater, that I never use . . .

  10. Back To Top    #10

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    nocaster,

    Ouch! that'll be a tough fix. Obviously, you need to restrict the flow from the pool into the skimmer but I can't picture anything that makes sense. I'd try hard to identify that skimmer model and give their tech folks a call....they may make something. Like HDTV, my skimmers have entrance and exit ports on the dead bottom, well below the skimmer basket.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  11. Back To Top    #11

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    Gosh, I love this place. Now I know exactly what that little spaceship looking thingy really is and what it really does. Although, I once had to replace said spaceship looking thingy and when I described it that way to the pool store guy, he led me to the right thing. I had no idea that it was controlling the main drain suction/flow.
    Buggs

    14,000 gallon, in ground, plaster, free form, play pool.
    Sta-Rite Max-E-Glass with a 1.5 hp Emerson motor
    WaterCo Micron High Rate sand filter S750 490 lb, 4883 sq ft - using ZeoBest
    In floor Polaris cleaning system
    Blue Diamond robot for those after storm days when I can't wait overnight for the in floor to clean it.

  12. Back To Top    #12

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    After searching around I found a sta-rite/swimquip vacuum plate that fits over the basket. This should sit above the main drain hole. It has a fitting to put a hose on, but I could probably put a rubber stopper in it and get full flow from the drain. That would probably be good enough for brushing dead rolly pollies into the drain.
    20K IG Fiberglass, 3/4 hp Sand, Hayward ColorLogic

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