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Thread: DE/Bugs blowing in pool

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    DE/Bugs blowing in pool

    I moved into my first house 7 months ago, and it has a pool. I have kept the same pool service that the previous owner had since they had done some work on the pool and he was happy with them. When i signed the contract for the service, they tried to sell me a new filter, saying that my existing filter was too small for the pool and solar system. I have been hesitant to do anything since it sounded like a sales pitch rather than advice.

    For months i've been seeing DE in the spa, and I've had a big problem with bugs, and bug parts on floating in both the spa and the pool. I figured there was probubly a tear in one of the grids letting DE and some bugs through, so last week I had my filter serviced by the pool service company, and they replaced 3 grids and the standpipe O-ring, and they said that overall the old grids looked pretty good. I was hoping that would have fixed my problem, but there is still stuff blowing into the pool. I put filter bags over the returns, and saw lots of DE and bugs mainly coming through the spa return, so the problem hasn't been fixed.

    One wierd thing I have noticed is that the filter pressure is always high(25-30psi), probubly why the pool company thought i needed a bigger filter. One speculation I have is that the pump is too big. Some of the plumbing seems to be 1.5" which is probubly why i'm getting high pressure.

    I noticed my Navigator pool cleaner has never really worked as good as my brothers, and he told me to use the vaccuum gauge checker to check and make sure it's getting sufficient vaccuum. I hooked up the gauge to the cleaner hose, and it's no where near the recommended pressure, and the pump makes air bubbles in the strainer basket if I adjust the valvles to pull more from the pool cleaner.

    I'm going to take the multiport valve apart this afternoon and ckeck the gasket to make sure stuff isn't just blowing through it, causing my problem with bugs and DE.

    I'd really like some input or ideas from some more experienced pool owners or techs. I'm a DIY'er, so ditching the pool company and doing all of this myself doesn't scare me. My pool and equiments is all listed in my signature, please let me know what you think, or let me know if you need any more info.
    9000 gallon inground pool
    700 gallon overflow spa
    Pentair FNS Plus 24sq. ft DE Filter
    Sta-Rite Dura-Glas 1.5HP pump
    Sta-Rite Max-E-Therm heater
    288sq.ft solar panels
    Hayward Navigator Cleaner

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    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: DE/Bugs blowing in pool

    There is no question, your pump is too large for that filter. That would be why the filter pressure is so high.

    A pool that size doesn't normally need a pump nearly that large, but sometimes solar systems need larger pumps (depending on height and complexity). My guess is that ideally you want a larger filter and a smaller pump, but it is impossible to be sure without lots of details and calculations.

    Even with the oversized pump it should be possible to get the filter working correctly at least for a good while. The filter should not be letting anything you can see through. The oversized pump does put extra strain on the filter, but based on your pressure reading it shouldn't be enough to damage the filter right away, shorten it's life a little maybe but not break it outright.

    Of course, it might not be the filter that is broken. The multi-port valve can be broken in a way that lets water (and dirt) bypass the filter completely. Usually when that happens the multi-port valve also leaks some water into the backwash line at the same time.
    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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    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    30,083

    Re: DE/Bugs blowing in pool

    Welcome to the forum. Very thorough first post. Just to reinforce Jason's post, your pump is indeed too big. WE have some hydraulic experts here but .75 hp is gonna' be all the pump you need.

    I don't have enough knowledge on DE filters to help.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: DE/Bugs blowing in pool

    Thank you for the replies... As for my solar units, they are on the roof of my single story house, so they aren't way up there. They are about 40ft away from the pad though, so that might be something to consider. With the solar on, my pressure only goes up about 5psi, so they don't seem to add much load. Since my service company took apart the filter last time, I did not get to inspect it with my own 2 eyes, so I have no idea what's going on with the parts they put back in. I really wish I had done it myself now. I think i will take the filter apart next time it needs a backwash and thoroughly go over everything in the filter to make sure the manifold, o-rings and grids are all in good shape.

    Since I now know for sure that my pump is too big, can just swap to a smaller motor and impeller with my existing pump housing? If so, is there anywhere around the net that has good deals on motors? Or anywhere around where i can trade my 1yr old motor for a smaller one? I did some calculations and figured that a 1hp pump would be work for running the pool, spa and solar. Ideally, I would love a 2 speed motor, but they seem to be outragously expensive.
    9000 gallon inground pool
    700 gallon overflow spa
    Pentair FNS Plus 24sq. ft DE Filter
    Sta-Rite Dura-Glas 1.5HP pump
    Sta-Rite Max-E-Therm heater
    288sq.ft solar panels
    Hayward Navigator Cleaner

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    Join Date
    Oct 2007
    Location
    Philadelphia, PA
    Posts
    86

    Re: DE/Bugs blowing in pool

    For what it's worth, my pool is somewhat larger than yours (see my sig). I have similar DE filter and a 3/4 hp pump. I get excellent filtration and circulation even with a single skimmer and a single return. My feeling is that I could probably get by with a 1/2 hp pump, but pool pumps this small are not really available.

    Being you bought the pool with the house like I did, I can share some ideas. It's likely the previous owners never cleaned the filter grids. I recommend soaking the grids in water with a few squirts of dish detergent for several hours and then rinsing them well. If there are calcium deposits, you should follow the rinse with an acid soak and another rinse. I did and it greatly improved the efficiency of my filter.

    The pressure on my filter is 8 psi after backwashing and 10 psi after recharging with DE. I allow the pressure to go up to 18-20 psi and then backwash and recharge again.
    11x27 in ground, vinyl pool
    ~12,500 gal
    PAC FAB (Pentair) Pinnacle 3/4 hp pump
    Pentair 24 sq ft DE filter
    One skimmer, one return (no main drain)

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