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Thread: fine debris - seems like sand

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    fine debris - seems like sand

    just about every day I have fine debris at the bottom of my pool. to me it appears to be a very fine sand and it is always found down stream of the outlet port of our pump ( I have an elbow that I can make it go different directions ).

    our sand filter operates pretty much as I would expect from my reading. we start at 8psi and within a couple of weeks we get to 10-11 psi and then backwash it.

    we have large trees all around us and gain leaves / acorns all the time. we are pretty dilligent about cleaning the bottom almost daily and it wouldn't be very fun to swim without this work because of all of this litter in the pool.

    even when we haven't had leaves / acorns fall in the pool that fine debris is on the bottom.

    this is our first season of pool ownership and I don't really know what to expect. is this an indication of a poorly functioning sand filter?
    Jim -Nebraska
    12,000 Gallon, Vinyl In Ground
    Filter Flow Rate 120GPM, 3/4 HP pump
    Pool Built 1973

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    Mod Squad zea3's Avatar
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    Re: fine debris - seems like sand

    To check if it is really comming from the filter, you can hold a clean sock over the return while the pump is running and see if anything collects in it. It is also possible that it is latent algae. Could you post a set of current test results?
    TFP Moderator
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    Vogue 21' round AG, Pentair 1 hp 2 speed pump, 36 sq ft DE filter, Hayward S180T 150# sand filter, Houston, Texas
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    UnderWaterVanya's Avatar
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    Re: fine debris - seems like sand

    Get some knee high stockings and some rubber bands. Put a stocking on one or more of the returns using rubber bands to hold in place. Check back in a day or two (depending on how quickly you've been seeing the sand appear) and look in the stocking to see if there is any sand in them? If there is - then your filter is allowing sand to pass. This can be due to a number of things including broken laterals, a bad spider gasket in the multiport, etc. Find out if sand is getting trapped in the stockings first then check back with results and someone will be able to help from there.
    Inlaws Pool Boy since June 14th 2012, Pool built ~ 2003, In-Ground, 16'x32'
    13500 gal, Vinyl Liner, Fiberglass Slide, TF-100 Test Kit, Hayward 210T
    sand filter, A.O. Smith 1.5HP main pump motor (C48L2N134C1),
    Hayward SuperPump (model ?), Polaris 380 & PB4 Booster Pump

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    Re: fine debris - seems like sand

    Great, I will try the sock thing.

    My numbers are:

    CYA - 70
    TA - 120
    FC - ( struggling here, been bouncing around, but running between .5 and 3 )
    CC - < .5
    PH - 7.4
    CH - 320

    We have been seeing small splotches of algae in the last couple of weeks. Since we are cleaning very regularly with a triangle headed vacuum thingy that has brushes on it they get brushed off at the same time. I have also found algae around a light and the steps.

    I am a little embarassed that I didn't notice that my FC levels were recommended to be quite a bit higher with my CYA level and I have been targetting 2-3ppm instead of 5-8ppm. So yes, I think this could be the result of algae.

    I will report back on results ( stockings and adjusting my FC level after a shock round )
    Jim -Nebraska
    12,000 Gallon, Vinyl In Ground
    Filter Flow Rate 120GPM, 3/4 HP pump
    Pool Built 1973

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    Mod Squad zea3's Avatar
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    Re: fine debris - seems like sand

    It does sound like algae. If I allow my water to get a little cloudy and then bring the FC to shock level next morning I will find drifts of greyish dust on the floor of the pool. I also get a lot of tree debris in my water but the dust only shows up if I have allowed the FC to drop too low.

    Try keeping the FC at the top of your target range and only use liquid chlorine for the rest of the pool season. Pucks and powdered shock will raise your CYA and Calcium too high. Without a saltwater chlorine generator your CYA should be in the 30-50 range. With a vinyl liner you only need 50 ppm of CH, 320 is a little high but not unmanageable, however you do not want it to get any higher if you can help it. If you partially drain the pool to winterize that should help lower the high CYA when your re-fill in the spring.
    TFP Moderator
    Helpful links: TF Test Kits,TFP Pool School, PoolMath
    Vogue 21' round AG, Pentair 1 hp 2 speed pump, 36 sq ft DE filter, Hayward S180T 150# sand filter, Houston, Texas
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    Re: fine debris - seems like sand

    Intermediate update here. I am following the shock procedure and have struggled to get my FC up to 28. As of 9:15pm I am at 27.5 and will check my overnight usage.

    The debris was back in spades today, like my algae drifts were on their way to being dunes. I am thinking my inexperience is at play here and that this is simply algae and me not keeping my baseline FC at the right level.

    One thing I find odd is that twice earlier today my CC read 0 but this afternoon and tonight it was reading between .5 and 1.

    My plan is:
    1) keep FC as close to 28 tomorrow as possible ( shock level for my CYA )
    2) continue to vacuum and brush
    3) await sparkly waters
    Jim -Nebraska
    12,000 Gallon, Vinyl In Ground
    Filter Flow Rate 120GPM, 3/4 HP pump
    Pool Built 1973

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