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Thread: Blowing out Main Drain in Canada

  1. Back To Top    #1

    Blowing out Main Drain in Canada

    Hi All,

    I've owned a pool for 5 years now and we've always paid to have the pool opened and closed, mostly because we are afraid of the pipes freezing. Due to money constraints this year we decided to open and close the pool ourselves. The opening was easy and the close wasn't as difficult as I thought. I drained the pool down to about 3" - 4" below the jets and blew out all the lines using a 5 hp Rigid Vac. I have 3 jets so I blocked off 2 of them using rubber plugs while blowing out the third until nothing was coming out. I inserted foam rope as far as it would go into the three jets and then closed them off using the rubber plugs and then I went to work on my skimmer.

    From what I can tell my pool setup is different from others on this board because my skimmer has two holes in the bottom. The one closest to the pool goes down to the main drain and the other ones goes to my pool pump. (I don't have a main drain line to my pump.) From the reading I've done I tried to blow out the main drain line but couldn't get any bubbles to come out of the drain. I think I'm forcing water down because it isn't spraying in my face but I cannot get any air bubbles to come out of the drain no matter how long I blow it out. Because it was getting late in the day I closed off the main drain line with a rubber plug, blew out the other skimmer line with no problems and then sucked out any water that was in the skimmer. I finished winterizing the rest of the equipment (filter, heater, took the SWG cell inside) and then covered the pool with my winter cover.

    What I didn't have is any pool anti-freeze so I'm going to pick up some up this week and finish off the pool close next weekend but I have some questions.

    1) What do I do with the main drain line in the skimmer? I'm pretty sure the pool freezes solid in the winter but it's an 8 ft deep end which falls below the frost line so who knows if it freezes right down. I try to think back to when I opened the pool in the spring and I can't recall seeing any air coming out of the rubber plug when I removed it. I'm also not sure how I would get the rubber plug into the drain line in time. By the time I get the vacuum hose out of the way and then get my arm down into the skimmer any water I would've blown out would re-enter it.

    2) Every year when the pool company closes the pool, they wedge two small empty 1 L bottles and then use the half empty bottle of anti-free on top. Is this enough protection? I plan on shoving in a ton of foam rope in too but I don't have threaded fittings in my skimmer so I can't use a gizmo.

    3) I think they only use 4 L (one gallon) of anti-freeze when the close the pool. They use half the bottle in the pump basket and the other half in the skimmer. (In the jug.) Do I need to add more in the lines? I'm thinking if all the water is out of the lines and the rubber plugs are tight then I should be good.

    Sorry for the novel but I really don't want to screw this up.

    Any and all help you can provide will be greatly appreciated.

    18 x 44 AG pool 20,000 gallons
    sand filter

  2. Back To Top    #2
    Mod Squad JohnT's Avatar
    Join Date
    Apr 2007
    SW Indiana

    Re: Blowing out Main Drain in Canada

    A shop-vac or blower doesn't have enough power to blow the main drain. You need a compressor. But as soon as you turn the compressor off, the water will refill the line up to the water level in the pool unless you have a way to seal it off quickly. Something like a cap with a Schrader valve in it will work.

    I like to put antifreeze in each of the lines. It covers you in case there is a leak. I usually use about 4 or 5 gallons. None in the pump basket.

    You need to verify that your returns aren't bubbling after the caps are on, and that each one is sealed while air is blowing through it.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

  3. Back To Top    #3

    Join Date
    May 2007
    South Central NJ

    Re: Blowing out Main Drain in Canada

    A blow through extension will extend the hole above the water line. Blow out as much as your shop vac will allow and quickly cap the hole with a winter plug to trap the air below the frost line. An Ultra-Gizmo works too. There are also winter plug with what look like a tire's air valve in them that a compressor will work with too but you need the blow through extention. Alden Leeds Corp make blow through extensions and Anderson Leak Detection makes the plugs.

    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

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