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Thread: Pump pressure at 15 psi

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    Pump pressure at 15 psi

    I have a hayward GM series and a 1hp pump. The connections and piping is in good order. I backwashing the unit, however, it seems the operating pressure is at 15 psi. I don't know if this is normal. This is for a above ground 24' pool (48" deep). This is the first time using this filter and pump from the previous owner?
    13,500 gallon above ground round pool. Vinyl Liner. Hayward S244T 3.1 cu ft sand filter. Hayward Powerflo 1HP pump (single speed induction). HTH 6-way test kit.

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    Melt In The Sun's Avatar
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    Re: Pump pressure at 15 psi

    Just to be clear, it reads 15 psi when it's running normally, not when you're backwashing? If that's the case, that pressure sounds just fine to me! If the gauge doesn't go to zero when the pump is off, it should be replaced.
    11,200 gal, Pebble-Tec; Tristar 2-speed 1hp - Swimclear 325 ft2 cart - SWG - A & A in-floor cleaner - Heat pump. For the poolside cooking, a Yoder Wichita and a Big Steel Keg!
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    Re: Pump pressure at 15 psi

    Quote Originally Posted by Melt In The Sun
    Just to be clear, it reads 15 psi when it's running normally, not when you're backwashing? If that's the case, that pressure sounds just fine to me! If the gauge doesn't go to zero when the pump is off, it should be replaced.
    When it's running normally. I was told though you should backwash when the pressures between 10 to 15 psi. It seems the normal pressure in my filter is around 15 psi?
    13,500 gallon above ground round pool. Vinyl Liner. Hayward S244T 3.1 cu ft sand filter. Hayward Powerflo 1HP pump (single speed induction). HTH 6-way test kit.

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    Re: Re: Pump pressure at 15 psi

    Quote Originally Posted by steppinthrax
    Quote Originally Posted by Melt In The Sun
    Just to be clear, it reads 15 psi when it's running normally, not when you're backwashing? If that's the case, that pressure sounds just fine to me! If the gauge doesn't go to zero when the pump is off, it should be replaced.
    When it's running normally. I was told though you should backwash when the pressures between 10 to 15 psi. It seems the normal pressure in my filter is around 15 psi?
    I think they meant when the pressure RISES 10-15 psi above your normal pressure.
    Jason, TFP Moderator
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    Re: Pump pressure at 15 psi

    Just another note, since i inherited the filter. It's a Hayward GM series. I'm not sure on the sand life as well as other things in the filter. I used it all day yesterday and it seemed to be filtering (since I see dirty when i'm back-flushing). How can i check the sand life? Or are there overhaul kits they sell to rebuilt the valve seals etc???
    13,500 gallon above ground round pool. Vinyl Liner. Hayward S244T 3.1 cu ft sand filter. Hayward Powerflo 1HP pump (single speed induction). HTH 6-way test kit.

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    Re: Pump pressure at 15 psi

    Backwash when you see a 20-25% rise in the filter pressure from normal.

    Most on here never change the sand unless it gets so gunked up (from poor management) that it cannot be cleaned. No refurb kits that I am aware of. Many sand filters go a decade with no problems. I am in year seven on mine and so far, no leaks and no problems.
    Dave S.
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    Re: Pump pressure at 15 psi

    You should be able to get seals for the stem and the spider gasket for the valve head. After you backwash your filter don't backwash agian until you have a minimum 10 lb rise on the filter gauge. Do make sure the gauge is good.
    Over 30 years in the pool business
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    Re: Pump pressure at 15 psi

    Quote Originally Posted by swimcmp
    You should be able to get seals for the stem and the spider gasket for the valve head. After you backwash your filter don't backwash agian until you have a minimum 10 lb rise on the filter gauge. Do make sure the gauge is good.
    Yes, I know the gauge is good, because I just got my new gauge yesturday and replaced it. This is why I'm questing these pressure readings. I was running it last time on a broken gauge.
    13,500 gallon above ground round pool. Vinyl Liner. Hayward S244T 3.1 cu ft sand filter. Hayward Powerflo 1HP pump (single speed induction). HTH 6-way test kit.

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    Re: Pump pressure at 15 psi

    After you backwash your filter don't backwash agian until you have a minimum 10 lb rise on the filter gauge.
    While that will work, the chances are good you will be not be filtering very effectively for a long period.

    Mas985 has done some work on this and his suggestion is that a percentage rise will give you better filtering efficiency. If your normal psi is 8 and you wait until you get to 18, your flow will be down so much that you will not be pushing much water.

    Of course, backwashing too frequently will waste a lot of water and time. In any event, rather than a specific psi increase (because all starting psi's will differ) the percentage increase seems a more effective way to go.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: Pump pressure at 15 psi

    Is the percentage rule applicable to DE filters as well as sand filters?
    Jason, TFP Moderator
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    Re: Pump pressure at 15 psi

    Certainly. You are measuring an increase in the resistance to the pump caused by dirt being caught so I would apply it to all three filter types.

    I would also be reluctant to call it a rule. BBB is about understanding your pool's chemistry, equipment, and the way it functions. With that understanding, comes the ability to know your pool better than anyone else and be able to decide what will work best for your situation.

    I would say it is a guideline that makes a little more sense than a hard psi number. I can't remember for sure, but mas985 may have even suggested a somewhat lower percentage.
    Dave S.
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    Re: Pump pressure at 15 psi

    The biggest issue I see is that the higher the filter PSI rise, the lower the flow rate through the filter. If you let a filter rise 10 PSI, that is over 23' of EXTRA head loss which can bring any pump to a very low flow rate and the amount of water filtered for a given run time is greatly reduced. This is somewhat offset by the fact that filters tend to filter better the dirtier they get. But an increase in filter pressure and a reduced flow rate can also cause problems with skimming, cleaners and solar systems.

    The reasoning behind the percentage PSI rise rather than the absolute PSI rise is that not every plumbing system runs at the same PSI. This is especially true with VS pumps. Going from 20 PSI to 30 PSI is much different than going from 10 PSI to 20 PSI and the two filters would be at different levels of being dirty. 25% rise is a reasonable upper limit but this needs to be balanced with the frequency of cleaning. Nobody wants to clean a filter too often.
    Mark
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