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Thread: New to board, need help with pipe size and clarity issues

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    New to board, need help with pipe size and clarity issues

    Hey all, i'm new to the board but am hoping I can find some feedback from those much wiser than I. I've been operating pools (public/commercial) for years, but I seem to have met my match.

    A little background, the pool is a rectangular indoor pool, 55K gallons, no deep end. The pool was originally built by a Gold's Gym and was built from what I can tell for the occasional lap swimmer and group aquatics class. Not surprisingly, Gold's had no idea what they were doing and my non-profit organization has purchased and owned the facility for the last three years. Needless to say, our bather load is significantly higher than anything Gold's ever experienced.

    My problem is clarity. I've had to go to the extreme of shutting the pool down for two days to do a 3/4 drain and refill as well as use clarifier, and everything was fine for about 1 month and the cloudiness has returned. We have two sand filters that aren't more than a year old, chemicals are all balanced, no channeling in the filters, everything I can see and go off of from my background looks good.

    Now, my question is this. I believe the problem with our inability to keep the pool water clear lies in the fact that the pool wasn't built for our bather load. I suspect that the main drains are getting overwhelmed by the skimmers and here is why:

    - 4 skimmers come into one 3 inch line to the pump
    - 2 intakes from the bottom main drain come into one 1 inch pipe to the pump
    - 1 pipe that's usually closed for the vacuum

    When I close the skimmer valve completely, the system loses pressure and while water still comes into the pump, it's obvious that the pump isn't pulling nearly enough. But when we open the skimmer valve about 25% the pump fills and the system has no air in it.

    Could the fact that my 4 skimmers are coming into my pump in a 3 inch line and my main drain coming in with a 1 inch line be the cause of my clarity issues? I'm of the opinion that the skimmers overwhelm the main drains and 98% of the water going though the filters is from the skimmers and not pulling from the middle of the pool.

    Suggestions or comments?

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    duraleigh's Avatar
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    Re: New to board, need help with pipe size and clarity issue

    Welcome to the forum.

    Water issues can only be wildly guessed at unless you can give us some current test results.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Charlie_R's Avatar
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    Re: New to board, need help with pipe size and clarity issue

    What have you been using to test with?
    15'x48" 4500 gallon Intex pool, buried 1.5 ft. Pac-Fab Dynamo 3/4 hp pump. Hayward S180T sand filter, bought used. Taylor K-2006 test kit. Rocket mass heater based wood fired pool heater.

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    Re: New to board, need help with pipe size and clarity issue

    As duraleigh said, we really need your full test results that have been done with a good test kit.

    In addition, we would need to know as much as possible about your operation. Things like bather load in person hours, water temperature, measured flow rate, chemicals used etc.

    I find it hard to believe that anyone would build a pool where the two main drains went to a 1-inch line. That would not pass any building code that I know of.

    Are you required to have a permit from the city to operate? Have you been inspected and passed?

    Are you using bromine? If yes, how many pounds have you used total?

    An indoor, high bather load pool or spa is one of the most difficult challenges for a pool operator. Other than clarity, what water quality issues have been raised? Things like smell, burning eyes, rashes etc?

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    Re: New to board, need help with pipe size and clarity issue

    Ok i'll try to answer all questions but forgive me if I miss some.

    Yes, we are inspected by the department of health on a regular basis, never been shut down. We are required to submit for a public bathing cert and renew it annually with no issues.

    Keep in mind, this pool was built by Golds Gym and now we (the YMCA) have taken over the building and remodeled, but based on our completely different target markets, we have kids and families and Gold's just doesn't have that clientele.

    We use liquid chlorine and dry acid to balance ph and cl.

    The most recent readings from today are:

    cl - 3.5
    pH - 7.4
    Ca Hardness - 150
    Alk - 100
    Temperature - 84
    Saturation Index - -.2

    The pool as I stated is 55K gallon indoor rectangle pool, open from 5:30am until 9:30pm at night M-F, Saturdays from 7a-7p, Sundays from 9a-7p. We cap total swimmers in the pool at one time at 30, and on average during the week we see traffic from about 150 people daily (could be a low estimate as I don't have exact numbers) and another 300 on Sat/Sun.

    102 Total operating hours weekly
    1050 people average weekly users
    The pool is hooked up to a heater and the temperature is regularly kept at 84 degrees with little variation from that setting.
    I'm running 100 gpm flow. At 55K gallons, that's a little over a 9 hour turnover rate, which I don't think satisfies Maryland state regs for public pools turnover rate. I believe the minimum is 6 hours for the state. In my opinion, i'm not turning over the water at all, but that's just a hunch and why i'm here asking this brilliant bunch of people to save me from further hair loss!!! =)

    I should also state that this has been an ongoing issue with this pool, though i'm just now becoming aware of it as I've just recently taken over this facility. It's also gotten worse as our membership base has grown, obviously so has our bather load. So with continued growth for the foreseeable future, I'd really like to permanently solve this nagging clarity problem, but I have little faith in the pool vendors we've been using up to this point and the one we are using, while a really nice guy, has already installed a two-tank sand filter system this time last year as the "permanent solution" to this problem, yet here we are a year later still having the problem.

    My fear is that because of how Gold's gym built the pool with a 3 inch line for 4 skimmers and 1 inch line for 2 bottom drains, my last resort is going to have to be digging up the piping system and fitting the proper sizes.

  6. Back To Top    #6

    Re: New to board, need help with pipe size and clarity issue

    Missed one, no the only issue we have is the clarity, no burning, smell or any other issues.

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    mas985's Avatar
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    Re: New to board, need help with pipe size and clarity issue

    First, plumbing has little to do with water clarity. Clarity issues are most often caused by chemistry issues.

    Is any CYA used in the pool?

    Did you check combined chlorine levels?

    As for the clarity, how would you describe it? (e.g. milky)
    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: New to board, need help with pipe size and clarity issue

    If the pool is painted, then it might be paint dust rubbed off by swimmers.

    You might need/want to go to a supplemental sanitation system, such as ozone or UV.

    Your turnover time is too long. You need to decrease it to, at least, meet the regulations.

    I would switch to DE filters to get better filtration.

    Regarding the 1-inch main drain line. I'm thinking that there might be some misunderstanding. I really find it difficult to believe that any pool built in the last 20 years could have any 1-inch suction lines. Can you post a picture of the plumbing?

    Note 1: If there is ever a time when you cannot clearly see the main drain, I would recommend that the pool be immediately closed until the clarity improves.

    Note 2: It can be difficult to diagnose problems like this without an on site evaluation. It might be worthwhile to have a new pool company come in to review all aspects of your operation and advise you.

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    Re: New to board, need help with pipe size and clarity issue

    Yes I had planned on getting at least two other opinions. Ill post some pictures of the pumps and the water later today but I'd describe the water as somewhat milky. We do regularly keep the skimmer valve partially closed to allow more water to pull and filter from the main drain. The pool surface is not painted. We can see both main drains but as you pointed out, as safety and risk as our absolute priorities, we haven't hesitated to close the pool when we've felt it's not conducive for a lifeguard to keep swimmers safe. Usually at that point we do a partial drain and refill.
    We have toyed with the idea of dropping at DE filter in at night but in an attempt to find a permanent solution haven't gone that route just yet.

    Ill post pictures in a little bit once I get to work.

    I appreciate all of your help!!!

  10. Back To Top    #10

    Re: New to board, need help with pipe size and clarity issue

    I would keep the skimmer fully open. If the main drain really is undersized, you are restricting the flow too much.

    What size sand filters do you have?

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    mas985's Avatar
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    Re: New to board, need help with pipe size and clarity issue

    Combined chlorine level?
    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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