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Thread: Sand Filter vs. Sediment - Need Help

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    Sand Filter vs. Sediment - Need Help

    Time to solve this mystery that has been plaguing our pool for the past 2 years. There is a fine layer of sediment that builds up around the edge of the pool pretty much every day. If I brush it up, the water turns cloudy, and the next day after filtering it's sitting on the bottom like a brown halo.

    I've been holding a FC level of about 17 for the past week, so I don't think it's algae.

    Is it sand? Is it time to replace the sand in our Tagelus TA40D? I did flush it out with a hose a few seasons ago.

    Not sure what the problem is but I'd love to get rid of this constant sedimentary companion.

    Thanks!

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    11,000gal, in-ground, concrete, sand filter, 3/4 HP pump, TF-100 Test Kit, Austin Texas

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    Re: Sand Filter vs. Sediment - Need Help

    I am curious about this as well. I get this same stuff at the bottom but I have a cartridge filter. I have vacuumed mine out and it just seems to come back. The only though I have is loose dirt getting blown into the pool and settling at the bottom.
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    Re: Sand Filter vs. Sediment - Need Help

    What happens if you vacuum it up into the filter? Are you brushing the walls? Can you post a full set of test results....including CYA?
    Dave S.
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    Re: Sand Filter vs. Sediment - Need Help

    If it were occasional or seasonal depending on the prevailing winds I might think West Texas dust, you are a couple of hundred miles or so(?) east of the region where it coats everything, but that is not to say that if the wind is blowing right that you would not get some in Austin.
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    Re: Sand Filter vs. Sediment - Need Help

    Dave, here are a complete set of test results. These are all done with brand new chemicals that I ordered last month The only tricky one is the CYA test. Ironically last week while I was trying to measure it, I totally lost the slender beaker! So for this test today, I used a crude method of filling the regular plastic cylinder instead until I could no longer see the bottom. It dissappeared at about 30ML (I dumped in an entire bottle of stabilizer bought at Home Depot last week - something I do every season).

    Another note, I have twice recently gone around the edges and vacuumed the offending sediment straight to waste, but it reappears. And yes, I am brushing the walls often.

    Here are the results minus CYA which I discussed above:
    FC = 18
    CC = 1
    TC = 19
    PH = 7.5
    T/A = 290
    CH = 200

    Thanks!
    11,000gal, in-ground, concrete, sand filter, 3/4 HP pump, TF-100 Test Kit, Austin Texas

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    Re: Sand Filter vs. Sediment - Need Help

    Maybe holding that FC level of 17 isn't quite enough because you still show a CC of 1. Have you performed the overnight chlorine loss test?
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    Re: Sand Filter vs. Sediment - Need Help

    Not yet. Since I just did my first actual test with new chemicals last weekend, I've just been kind of dumping in jugs of bleach 3 and 6 at at time. Maybe I need to take a more concentrated effort?
    11,000gal, in-ground, concrete, sand filter, 3/4 HP pump, TF-100 Test Kit, Austin Texas

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    Re: Sand Filter vs. Sediment - Need Help

    Quote Originally Posted by Chappy
    Not yet. Since I just did my first actual test with new chemicals last weekend, I've just been kind of dumping in jugs of bleach 3 and 6 at at time. Maybe I need to take a more concentrated effort?
    Yep, follow the shock process in Pool School and get that under control.

    What does that stuff feel like? Sand will feel gritty, algae will feel slimy & pollen feels squishy.

    I recommend a good filter cleaning like described here: my-sand-is-channeled-how-to-fix-it-t7626.html

    You can also put a sock over the returns to see if sand is coming back into the pool from/thru the filter.
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    Re: Sand Filter vs. Sediment - Need Help

    Maybe I need to take a more concentrated effort?
    My guess is it's dead algae and you need a more precise effort. Get your CYA test where you can use it. Then, when you have a decent CYA result, I think you might find your CYA is too high and, as a result, your chlorine has only been partially effective.

    Like Butterfly and Woody, I think you need to clean your filter well and probably take your FC much higher. Get some of that stuff in your hand and see if it's gritty. I think it'll be slimy....dead algae
    Dave S.
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    Re: Sand Filter vs. Sediment - Need Help

    I do think it's dead algae, it was slimy to the touch. I took the hose to the filter and cleaned it out for about 15 minutes until it ran clear, and then I upped the FC to about 38. Seemed to pretty much hold there over night. I've also had the pump running continuously.

    This may be a dumb question, but if it's all dead algae, how does shocking the pool get rid of it? (as opposed to live algae).

    And should I run the pump continuously for a few days until it's all sorted out?

    Thanks again.
    11,000gal, in-ground, concrete, sand filter, 3/4 HP pump, TF-100 Test Kit, Austin Texas

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    Re: Sand Filter vs. Sediment - Need Help

    but if it's all dead algae, how does shocking the pool get rid of it?
    Dead algae comes from live algae which is still in your pool. You must shock (and you must follow the shock process article precisely) or you will continually have dead algae junking up your pool. In short you are not killing it all.
    Dave S.
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    Re: Sand Filter vs. Sediment - Need Help

    Thanks. I just ordered another CYA tube so I can get an accurate reading. I'll do a precise shock treatment and see if I can't knock this stuff out once and for all.
    11,000gal, in-ground, concrete, sand filter, 3/4 HP pump, TF-100 Test Kit, Austin Texas

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    Re: Sand Filter vs. Sediment - Need Help

    I agree with the others. It's probably dead algae. If it looks like the dust bunnies under the bed, just in water, and it disintegrates when you brush it...it's algae. And if the water's clear, but this stuff keeps forming, you're right on the threshhold. You are keeping it at bay, but not killing it all. Take off for the weekend, or get a hot spell, and you'll probably find a green cloudy pool.
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    Re: Sand Filter vs. Sediment - Need Help

    Here's an update to my shock treatment over the weekend. Got the new CYA measuring tube and got an accurate reading before proceeding. Here were my pre-shock (Saturday) numbers:
    PH: 7.5
    FC: 10
    CC: .5
    CYA: 55
    TA: 280
    CH: 300

    I brought the pool up to about a 25 FC level throughout most of the day and brushed the walls. Then I had it up to 28.5 FC in the evening. In the morning, I recorded a FC level of 33. I have been running the pump continuously and brushing the walls.

    Just took a reading (Monday evening) and had a FC of 17 and a CC of 0.

    The water is looking better, with less and less of the dead algae to brush up each day. But when I do brush the pool, it gets pretty cloudy, like there's a thin layer of the stuff still covering the bottom of the pool.

    So can I safely assume that there's nothing alive in the pool and that I should just keep brushing and running the pump until the water sparkles? (seems like I'm still a ways off from sparkle though... I'm more at a less dingy state I'd say)

    Thanks.
    11,000gal, in-ground, concrete, sand filter, 3/4 HP pump, TF-100 Test Kit, Austin Texas

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    Re: Sand Filter vs. Sediment - Need Help

    I did not see the results of an OCLT which is 1 of the 3 criteria to stop the shock process:
    pool-school/overnight_fc_test
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    Re: Sand Filter vs. Sediment - Need Help

    FC was 28.5 Saturday Night and 33 Sunday morning. Isn't that the proper result you're asking about?
    11,000gal, in-ground, concrete, sand filter, 3/4 HP pump, TF-100 Test Kit, Austin Texas

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    Re: Sand Filter vs. Sediment - Need Help

    If it was done correctly, it is impossible for the FC to have increased.

    Either the water was not properly mixed before the Sat. night test, or chlorine was added after the Sat night test.
    Make sure to test at least an hour after any chemical addition.

    I would re-do the OCLT tonight to be sure.
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    Re: Sand Filter vs. Sediment - Need Help

    I did think that was odd - I probably took the test too soon after adding my last gallon of bleach for the day and it didn't properly mix.... I'll do another check tomorrow morning to see how it compares with my reading taken this evening. I'll get this precise shock process down if it kills me!
    11,000gal, in-ground, concrete, sand filter, 3/4 HP pump, TF-100 Test Kit, Austin Texas

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    Re: Sand Filter vs. Sediment - Need Help

    Best to let it mix for at least 1 hour with the pump on high after adding before testing at night.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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