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Thread: Sand Filter top blew off

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    Sand Filter top blew off

    Ok the top of my sand filter just blew off. I am not sure what to do. Here is the situation.

    The pool is an inground 25000gal built about 1976. I purchased the house about 10 years ago. I nursed along the equipment until it finally gave out. In 2007 I replaced the the sand filter and the pump. I bought them at Leslies I got a Hayward 1 1/2 HP pump and Hayward S244S Pro-Series 24-Inch Side-Mount. This past year the Hayward pump froze up so I took it and had it reconditioned. At the start of this pool season I could not get the pump to fire up. It was done.

    After having done some research I decided to go with a Pentair Intelliflo variable speed pump. I installed it about a month ago and had it up and running for the past month. I have been experiencing a high pitch squeal out of the sweep line inside the pool. But, it has been doing it for the past couple of weeks so I did not think that much of it. Was not sure how to fix it. It was only happening when the booster pump was on. About, 2 hours each day in the early morning.

    Today I turned off the pump and rotated the valve to backwash. Then turned the pump back on and as the pressure built up it blew the top of the filter off. I replaced the top and tightened it down only to have it blow off again. I have read two other post on this site where the tops blew off and know that it is not fixable.

    My question is do I need a larger filter for the size of the Pentair intellflo pump. I know that I should have 2" lines but I only have 1 1/2" comming out of the ground and returning to the pool. Because of the age of the pool I thought it would be ok. I try not to run the pump at the 3450rpm that it can achieve.

    Any help will be greatly appreciated.

    Johnfm43

  2. Back To Top    #2
    JasonLion's Avatar
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    Re: Sand Filter top blew off

    You need to configure the pump so that it is impossible for it to run at anything near it's top speed. There are max speed settings on the configuration pages. Unless you set that up properly it will cycle up to it max speed each time it is turned on, which stresses the plumbing, especially the filter.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Sand Filter top blew off

    I get that about not achieving the max speed. But any idea as to why the top blew. Could the valve have failed and not allowed the water to return thus blowing the top?

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    JasonLion's Avatar
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    Re: Sand Filter top blew off

    The filter is rated for 50 psi. If you exceed that the top is designed to blow off so you don't have a less controlled, more dramatic, explosion.

    The IntelliFlo, even at max speed is not capable of producing 50 psi. However, with the pump cycling on and off and reaching perhaps 40 to 45 psi each time it starts up, the stress on the filter is quite large. Eventually the seal on the cover weakens and then blows out at a pressure below it's design pressure. Technically this is a failure in the filter that should never happen, but in practice it does happen as design an materials are never perfect. If you limit the peak speed of the pump to something reasonable, the peak pressure should be around 20 psi (or less) and things like this should never be an issue.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  5. Back To Top    #5

    Re: Sand Filter top blew off

    Ok. How should I proseed. I know that I need a new filter as you can see from my images it split the seam at the lid. I have a temp fix with the pump running at a speed of 2200 rpm.
    I need to get this fixed in the next 5 days, as I leave for a job for the next 45 days out of the states. If I dont get this fixed m wife and kids will have a huge green pond in the back yard.

    What kind and size filter do you recomend. Brand, style, and size?
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    Mod Squad jblizzle's Avatar
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    Re: Sand Filter top blew off

    The type of filter is personal preference. There is an article in Pool School that discusses the types.

    Minimum size recommendation would be:
    370 sqft cartridge
    29" diameter sand
    70 sqft de

    You still likely should not ever run near max speed.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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