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Thread: Bottom Drain vs. Skimmer Adjustment

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    Bottom Drain vs. Skimmer Adjustment

    The pool is 16 years old. The previous owner of the house was there only one year and did not know the history of the pool. The pump suction has one return from the spa and one from the pool. Only one return from the pool, as opposed to one return from the pool drain and one from the two pool skimmers. The inside of the skimmers have some lettering that leads me to believe there was some mechanism to partially close off the skimmer and draw more water from the drain. If I set the pump suction to draw from the pool and not the spa, and then I plug off the skimmers, the pump loses pressure (0 psi). To me that means the drain is clogged. It may be a deliberate modification. Maybe the skimmer flow restricters became obsolete. When I sweep the pool, the drain does not seem to suck the cloud of debris pushed to the bottom.

    Are there service providers that could check out the drain and line without having to drain the pool?

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    Mod Squad Bama Rambler's Avatar
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    Re: Bottom Drain vs. Skimmer Adjustment

    Let's clear up some terminology first, so we can make sure we're all talking about the same things.
    Anything leaving the pool/spa going to the pump is a suction line.
    Anything leaving the discharge of the pump going to the pool/spa is a return line. (sucks from the pool, returns to the pool)

    So you have one suction line for the pool at the equipment pad (pump). And one suction line for the Spa at the equipment pad.

    Can you tell if both skimmers are plumbed together (i.e. If you block the front of one does the pump lose prime? My bet is that they're plumbed together.

    There should have been diverter in the bottom of one of the skimmers that allowed the main drain to flow in case the water level gets low. Without the diverter the main drain won't flow when the water level gets low even if it's open.

    Can you post a picture of the equip pad and in the skimmers?
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    Re: Bottom Drain vs. Skimmer Adjustment

    Bama, your interpretation is correct. The two skimmers are plumbed together. I can block one and the pump continues to put out pressure. If I block both then the pump pressure is zero. There is no diverter at the bottom of either skimmer. I have not been able to find any such device on the web and was hoping someone could direct me to what may have been originally installed and where I could find the component.

    So, is there some way to check or unclog the drain without draining the pool?

    Let me re-post my issue with the correct terminology:

    The pool is 16 years old. The previous owner of the house was there only one year and did not know the history of the pool. The pump has one suction line from the spa and one from the pool. Only one suction line from the pool, as opposed to one suction line from the pool drain and one suction line from the two pool skimmers. The inside of the skimmers have some lettering that leads me to believe there was some mechanism to partially close off the skimmer and draw more water from the drain. If I set the pump suction to draw from the pool and not the spa, and then I plug off the skimmers, the pump loses pressure (0 psi). To me that means the drain is clogged. It may be a deliberate modification. Maybe the skimmer flow restricters became obsolete. When I sweep the pool, the drain does not seem to suck the cloud of debris pushed to the bottom.

    Are there service providers that could check out the drain and line without having to drain the pool?

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    JasonLion's Avatar
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    Re: Bottom Drain vs. Skimmer Adjustment

    Do your skimmers have one hole on the bottom or two? Sometimes the main drain line joins up with the skimmer line underground, other times the main drain line shows up as a second pipe coming up on the bottom of one of the skimmers.

    It is possible to get a plumbing snake with a camera on it that gets pushed down the pipe to investigate what is going on, but hiring someone to do that can get expensive.
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    Re: Bottom Drain vs. Skimmer Adjustment

    Jason, you just made me think of something! If you recall, a while back I asked about my main drain not working. I posted a picture, but never heard any comments (it is OK, I know it gets busy here sometimes). I haven't had a chance to dive down with food coloring yet, partly because I forget, partly because I'm too lazy. We measured my drain this weekend and it's over 9' to the bottom, not fun to dive down and try to hold myself under while squirting some food coloring. Anyway, your post just made me think, I wonder if the leak detection people told me wrong (or maybe I misunderstood them) and my main drain is plumbed into the bottom of the skimmer! This plug with the tag on it is brand new it appears to me, and I did not put it there. I wonder if the leak people put it there to block off the main drain during testing and forgot to remove it! Is this the "second pipe coming up on the bottom of the skimmer" you are talking about, or at least is this what it would look like if it were?

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    Mod Squad Bama Rambler's Avatar
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    Re: Bottom Drain vs. Skimmer Adjustment

    I'm not Jason but that is certainly where it would be plumbed into if it was plumbed that way. That plug does appear to be brand new so it's possible that they just forgot to remove it.
    Dave J. TFP Moderator
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    Re: Bottom Drain vs. Skimmer Adjustment

    So now I have a physics question. I was actually a very good physics student back in high school and college, but it doesn't get used much in my IT field. I don't see how that can pull water from the main drain. It seems to me that the atmospheric pressure would all be in balance, so there would be no siphon effect... I just can't see how it would work!

    That said, I can't wait to get home and see if I can get my main drain working!
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    Mod Squad Bama Rambler's Avatar
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    Re: Bottom Drain vs. Skimmer Adjustment

    That's what the diverter is for. There's flapper in there that adjusts the amount of water that can flow through the skimmer so it puts a bit of suction on the MD so it draws. There's also a float in it and when the water level gets low the float seals off the ports from the outside world and makes the water flow come from the MD.
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    Re: Bottom Drain vs. Skimmer Adjustment

    This sounds just like the situation I had with my last pool in MA. The main drain line had a leak under the pool so they had plugged each end and abandoned it. You need to be sure that isn't the case before you remove that plug.
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    Re: Bottom Drain vs. Skimmer Adjustment

    The leak crew found zero leaks during pressure testing. They also went down to the drain and sealed it off, then filled the system with air. I think I found the reason they didn't remove the plug though, it won't come out! I wrench a lot and can turn a pair of pliers, but there's not enough room in there to get the pliers to where I can turn the thing. I'm going to have to figure out a way to get a 1 1/4" square socket (probably have to MAKE it) in there to turn the thing out.

    Bama, is the flapper somewhere I can't see? Because there is certainly nothing at the top. If it is somewhere I can't see, it stands to reason that plug needs to remain in place? I'm still confused.
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    Mod Squad Bama Rambler's Avatar
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    Re: Bottom Drain vs. Skimmer Adjustment

    The flapper is not in that picture. it's in the diverter, which is missing completely.
    Dave J. TFP Moderator
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    Hark's Avatar
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    Re: Bottom Drain vs. Skimmer Adjustment

    If you go to the pool school link and click on visual encyclopedia, scroll through the pictures, about 2/3 the way down you will see a picture of the main drain diverter.

    It is a round disc that fits into the skimmer right under the basket.

    The main drain question was driving me nuts when I first moved into my house too. Thanks to TFP, we figured it out.
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    Re: Bottom Drain vs. Skimmer Adjustment

    To late to take a picture today. Both my skimmers have only one port on the bottom. It's a riser where I can connect the vacuum hose. The riser is offset, i.e. not centered in the skimmer. The riser is plastic and has an integral pointer as part of the plastic. Visualize the symbol for the male gender, a circle with an arrow. On the floor of the skimmer on the side of the riser is text saying, fill drain. 180 degrees on the other side of the riser the floor says, fill skim. The text letters are cast in the plastic. I'm guessing that the riser is suppose to turn in order to adjust some type of diverter under the skimmer. But, I did not want to force it and break the riser without finding someone to confirm how this thing is suppose to work.

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    Richard320's Avatar
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    Re: Bottom Drain vs. Skimmer Adjustment

    Quote Originally Posted by RobbieH
    The leak crew found zero leaks during pressure testing. They also went down to the drain and sealed it off, then filled the system with air. I think I found the reason they didn't remove the plug though, it won't come out! I wrench a lot and can turn a pair of pliers, but there's not enough room in there to get the pliers to where I can turn the thing. I'm going to have to figure out a way to get a 1 1/4" square socket (probably have to MAKE it) in there to turn the thing out.

    Bama, is the flapper somewhere I can't see? Because there is certainly nothing at the top. If it is somewhere I can't see, it stands to reason that plug needs to remain in place? I'm still confused.
    Try a basin wrench. Or if you know a mechanic who deals with heavy-duty stuff, he may have a 12 point socket that will fit. Something like a 1 3/8 (or maybe a little bigger) hex socket will fit on a 1 1/4 square
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    Re: Bottom Drain vs. Skimmer Adjustment

    I have a 1 1/2, a 1 1/8, but nothing inbetween! So, here's me... I'll be buying one. I work on too much stuff in the shop to NOT have the right tool!

    Thank you for the diverter info, if it turns out this is the main drain feed, I'll get this resolved. No wonder I couldn't picture how the heck it worked.

    I feel I have the chemistry down, my next goal is to learn all my flow stuff!

    Thanks all, I hate the pool store!
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