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Thread: want to get main drain working

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    want to get main drain working

    Hello all,

    I have posted numerous times on other pool sites to no avail.

    I have a 60,000L inground pool with two returns, 1 skimmer, 1 main drain, an old duraglas pump, and swimquip filter. I want to get the main drain working to get more adequate circulation. For the record, the skimmer is a Jacuzzi Model W.

    The main drain is plumbed into the bottom of the skimmer, and there is a moveable flap what has a couple of positions on it. There are 3 settings, 1, 2, 3, and max skim, which probable relates to skimming somehow. The other position says vacuum, which its in now. If i'm not mistaken, I should need some sort of skimmer float to get a 50/50 mix of skimmer and main drain.

    Any input would be appreciated.
    11,000 gal inground fiberglass pool
    Aquarite SWG system

  2. Back To Top    #2
    Mod Squad Bama Rambler's Avatar
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    Re: want to get main drain working

    First thing to do is to post a picture of the inside of the skimmer.

    IIRC, On vacuum you should get no flow from the MD (Main Drain) and all the flow from the skimmer. It's about the same on max skim. 2 & 3 shoud be a mix of skimmer and MD. 1 should be almost all MD.

    To get the best performance from the MD just leave the vac plate in place and set the flap to your liking.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  3. Back To Top    #3

    Re: want to get main drain working

    Thanks for the reply,

    I went ahead and took a picture of the skimmer when the pump was off, and of the vacuum plate. This is the plate that is normally connected to my vac hose when I vacuum the pool.

    So if I want to get the MD working (if its not clogged with solid stuff), all I gotta do is move the flap to whatever position and drop the plate in right? Will the system still be functional with the basket in place?

    Thanks for the input.

    [attachment=1:1gfj15x3]skimmer.jpg[/attachment:1gfj15x3]
    [attachment=0:1gfj15x3]vacuumplate.jpg[/attachment:1gfj15x3]
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    11,000 gal inground fiberglass pool
    Aquarite SWG system

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    Mod Squad Bama Rambler's Avatar
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    Re: want to get main drain working

    If you move that little flapper to expose the hole it's covering and then set the vac plate in place it'll pull more from the MD and still pull some from the skimmer. Is there a flapper under the second hole in the vac plate?
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: want to get main drain working

    That second hole beside the center hole in the vac plate is machined there for some reason. The underside is just like a regular vac plate.

    Now should the vac plate go below or ontop of the basket? And what setting should I put the flap at when I figure out which way it pivots? Thanks.
    11,000 gal inground fiberglass pool
    Aquarite SWG system

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    Mod Squad Bama Rambler's Avatar
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    Re: want to get main drain working

    It goes on top of the basket. I'd start with the flap on 2 or 3 but it doesn't really matter. THe object is to have a little flow through the MD and good action from the skimmer.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: want to get main drain working

    Ok I was tinkering around with the skimmer today, and found a few things out.

    First of all, I found out from the diagram below that this "flap" I am always talking about is actually called a trimmer plate.

    So this is what went on. When I moved the plate to expose the MD hole, like I said there are a few positions to put it. 1, 2, 3, and MAX SKIM. When I put the plate in the positions 1-3, they all slightly covered the hole returning to the pump. It didn't look right to me, so I put in MAX SKIM, which had both holes wide open. I started the pump, and dropped the vac plate in. It sucked into place, and seemed to be working fine. Although I couldn't tell how much suction came from the MD. Then I noticed that every so often a vortex would be created, sucking air back to the pump. This didn't look right either, so I shut it down, and put it back to the way it was before.

    I don't quite understand why they would have trimmer plate covering the return port when it is in in positions 1-3.

    Although this may not have any relation to the problem, I am missing what seems to be the weir parts for this skimmer. They are outlined in the diagram below. All that came with the skimmer was the vac plate and the basket.

    Heres a pic:
    [attachment=0:14h0bssk]jbe0033-1.gif[/attachment:14h0bssk]

    Hopefully somebody can help on this mind-boggling dilemma. Thanks
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    11,000 gal inground fiberglass pool
    Aquarite SWG system

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    Mod Squad Bama Rambler's Avatar
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    Re: want to get main drain working

    It sounds like it's plumbed wrong. Don't worry about the numbers. When it's on Max-Skim the MD hole should be completely covered. From there it should be partially covered but the pump line should never be covered.

    It could be that the MD line is blocked and you'll need to try and find out if it's just a blockage or if it was plugged on purpose.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  9. Back To Top    #9

    Re: want to get main drain working

    Actually when its in the position MAX SKIM, both holes are wide open. The position vacuum is where the MD port is completely covered.
    [attachment=0:1e4wsv9i]DSC00516.JPG[/attachment:1e4wsv9i]
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    11,000 gal inground fiberglass pool
    Aquarite SWG system

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    Mod Squad Bama Rambler's Avatar
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    Re: want to get main drain working

    The Max-Skim setting is going to give you the max you can get from the MD. If you want it to pull 100% from the MD you need to install the vac plate and plug the top hole in it. That will make it pull 100% from the MD. I wouldn't think you'd want to leave it like that but it'll tell you if the MD is plugged.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  11. Back To Top    #11

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    Re: want to get main drain working

    Welcome to TFP!!

    What you want to do is leave the flap in the bottom of the skimmer on "full skim" at ~ all times (if you get a lot of debris on the surface, you can set it to "vacuum" to help the skimmer pull in as much of the stuff as possible - and without a weir, your not doing too much )

    The flap on the vac plate is to adjust the suction when you're vacuuming - you normally don't want to vacuum using full skimmer (the vac head will stick to the floor from having too much suction) - that's why they put the flap on the vac plate. You can adjust the flap to get optimal suction for vacuuming (optimal suction is achieved by setting up the vacuum with the flap wide open and adjusting that flap so you get 1/2 - 1 psi drop on the filter gauge- this gives you sufficient suction on the vac but won't have the vachead stick to the floor)
    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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