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Thread: Sand filter Very High Pressure

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    BrianT.'s Avatar
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    Sand filter Very High Pressure

    Hello All,

    New to the forum... glad to be here!

    Our pool had been shut down over the winter (pump bearing going bad) and the pool was in bad shape. It is not caged and we have trees nearby so it had accumulated a lot of "stuff".
    After a couple of hours of heavy material removal with a pole and net, I installed an "almost new" Hayward sand filter with new sand and began the cleaning process. After vacuuming and back washing it was time for the chemicals and brushing. The filter and cleaner for a few days and the water looks great.
    The filter however seems to be rebelling. When I backwash it flows nice and steady, however on filter cycle the pressure is through the roof (near 30).
    I have had this pool with a DE filter for many years and I got to know it very well... it was just time to retire it. This is my first time using a sand filter and from what I read they require less maintenance that a DE.
    I recently did a deep filter cleaning following the instructions from the video hoping that would help but to no avail.
    Could the tubes in the bottom of the tank be clogged with debris because of the initial cleanup?
    I probably should have filtered to waste instead of to the new sand but it would have wasted a tremendous amount of water to get it clean.

    My next step is to remove the sand and start from scratch... any thoughts?

    Thanks guys
    18k gal. IG, Plaster/Diamond Bright, 1 hp Flotek pump, Hayward S310T sand filter, Great White auto cleaner and inline chlorinator.

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    JasonLion's Avatar
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    Re: Sand filter Very High Pressure

    I can think of a few possibilities: you might not have not have backwashed long enough, there might be a valve somewhere out of position blocking the flow, or the gauge might be broken.

    The first test is to feel the return jet strength. If the return jets are as strong as always then it is probably a bad gauge.

    How long did backwashing take? After that vacuuming up I would expect 5+ minutes of backwashing before the water ran clear.
    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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    BrianT.'s Avatar
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    Re: Sand filter Very High Pressure

    The valves are inline open and the water from backwash after about 4 minutes is nice and clear. The suction from the skimmer is nearly zero during filter cycle but strong on backwash so that negates a clog I would think.

    I"ll try another backwash but I'm not optimistic.

    Have you ever heard of the laterals being clogged?

    Thanks
    18k gal. IG, Plaster/Diamond Bright, 1 hp Flotek pump, Hayward S310T sand filter, Great White auto cleaner and inline chlorinator.

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    JasonLion's Avatar
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    Re: Sand filter Very High Pressure

    It is possible in theory for the laterals to get clogged, but I've never heard of it actually happening.

    Here are two fairly obvious things, as sometimes you might have overlooked the obvious: make sure the skimmer basket and pump strainer basket are both clear of debris.

    If you have a multi-position rotary main valve, try turning it to recirculate. If the flow is good in recirculate and bad in filter then it is certainly a problem with 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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    BrianT.'s Avatar
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    Re: Sand filter Very High Pressure

    I'm just sitting here shaking my head...

    Let me explain. When I changed over to the sand filter I decided to install an inline check valve as a back flow preventor between the chlorinator and filter to prevent chlorine from getting to the gasket of the multiport. And it worked... until it didn't. I cut it out and low and behold pumping out with pressure of 10 again!

    Anyway, I know you're probably shaking you're head about right now too... go ahead, I deserve it.

    Thanks again
    18k gal. IG, Plaster/Diamond Bright, 1 hp Flotek pump, Hayward S310T sand filter, Great White auto cleaner and inline chlorinator.

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    JasonLion's Avatar
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    Re: Sand filter Very High Pressure

    Don't feel too bad. That is not as bad a gluing on a union but forgetting to put the locking ring on the pipe first. We all make mistakes now and then.
    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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