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Thread: sand/dead algea in bottom of pool?

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    sand/dead algea in bottom of pool?

    Hello to all in the known how.
    First time poster, long time reader. Bought a house a few years back and maintaned a trouble free above ground, vinyl liner, 21" pool for those few years. This year upon opening the pool after our winter, everything was reconnected as usual and water was balanced as per pool store recommendations and water was crystal clear and balanced with in 48 hrs. Since opening the pool, over time little dark cloudy dust forms in patches around the pool, it appears to form in the direction of the water flow from the return line. I've since vacuumed it on drain and clean once again. Although this dust reappears over time. At first it's in very little patches of dusty dark spots, sometimes greyish white, once brushed, the seem to dissipate but I'm not sure if they go away or just fall right back on the ground. At first I thought ok, sand in filter change. That was done and manifold was carefully inspected and appears to be in good shape. No water leaks anywhere and pressure gage works adequately. Still, this sandy stuff still reappears. Since opening the pool, vacuuming to waste has become a weekly event now (kind of a drag!) and if I dont vacuum, the entire floor will fill with this slimy dusty stuff, in patches in circular direction. Back washing every week now after every vacuum even though pressure gage isn't above 15, the clear bubble indicator shows alot of stuff getting backwashed. I backwas for 5 minuts and rinse for about 2 minuts. This was also done when the sand was changed (the right amount was used).

    Any help or advice would be greatly appreciated. I've even considered replacing the filter to a cartridge system, because I don't know how old the filter is, but I'm sure it's still in good condition.
    21' above ground pool.
    40000L
    1.5 HP pump

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    DCAG's Avatar
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    Re: sand/dead algea in bottom of pool?

    If you could suck some up into a turkey baster, or something similar, then put it into a glass jar, you could better determine if it's sand from the filter, or algae. Then you could get mechanical help, or chemical help.

    Also post details about your pool, and test results.

    Dan
    16' X 24' Wilkes Pools "Genesis", 10K Gal
    Hayward Powerflo Matrix 1 hp, & 18" Pro Series sand (S180T)

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    Re: sand/dead algea in bottom of pool?

    from what i can gather just by brushing it... looks alot like dead algea but it's hard to tell

    chlore: 1.5ppm
    ph: 7.2
    alcalinity: 10ppm
    hardness: 250ppm
    these tests were performed at a local pool store this afternoon
    21' above ground pool.
    40000L
    1.5 HP pump

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    reebok's Avatar
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    Re: sand/dead algea in bottom of pool?

    what about cya/stabilizer? if your alkalinity is truly 10 then you need to raise it with baking soda.
    pool-school/recommended_pool_chemicals
    to figure out how much to add, use www.thepoolcalculator.com
    you'll probably need a lot more chlorine too. did they do an fc and cc test? honestly those are some of the poorest pool store test readings unless you just aren't including all of them in your post.
    16x32 21,000 gallon in-ground exposed aggregate, 1.5hp pump, 120 sqft catridge filter, birdcage, solar panels, aquavac tigershark qc robot.

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    Re: sand/dead algea in bottom of pool?

    no that's all the info they provided with
    sorry alcanilty is 100 not 10.. was a typo
    a stabilizer was used early in the pool season
    21' above ground pool.
    40000L
    1.5 HP pump

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    reebok's Avatar
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    Re: sand/dead algea in bottom of pool?

    there's not really an option to not knowing your cya level if you're going to use this method. I mean you could shoot in the dark, but if you're wrong you're wasting any money spent. this is one of the reasons the site recommends getting a good personal test kit, so you can know your numbers and take control of your pool.
    pool-school/pool_test_kit_comparison
    I highly recommend the tf100, it's a much better value.
    16x32 21,000 gallon in-ground exposed aggregate, 1.5hp pump, 120 sqft catridge filter, birdcage, solar panels, aquavac tigershark qc robot.

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    Bob_Funk's Avatar
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    Re: sand/dead algea in bottom of pool?

    Quote Originally Posted by helpmeplease
    a stabilizer was used early in the pool season
    How much CYA did you add?
    I consider myself very lucky I found this site before the pool store found me-pool owner since Nov 2008- Stunningly clear 17,000 gal fiberglass pool, thanks to this site, installed in 1982-24" 3.1sq. ft sta-rite sand filter, 1 hp - 2 speed wisperflo pump-WFDS-4

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    dmanb2b's Avatar
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    Re: sand/dead algea in bottom of pool?

    with "chlore" at 1.5 it very well could be algae...it's too low. As reebok suggested pool school and a good test kit will get you on the right track.
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

    Pool School, TFTestKits, Pool Calculator

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    Re: sand/dead algea in bottom of pool?

    Quote Originally Posted by Bob_Funk
    Quote Originally Posted by helpmeplease
    a stabilizer was used early in the pool season
    How much CYA did you add?
    if i remember correctly it was 1.5 kg of stab for 40000L.

    today i vacuumed the pool again and was all clean till the pool pump/filter went on for it's daily run... well seems that the bottom of the pool only gets dirty when the pool pump/filter run.. i guess that is a clear indication that the filter is not running properly is it not?
    i see no dirt or dead algea forming or accumulating when the pump/filter are off...
    21' above ground pool.
    40000L
    1.5 HP pump

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    Re: sand/dead algea in bottom of pool?

    after shocking last night, the chlore level was raised to 2.5ppm... will minitor any drop during the coarse of the day
    21' above ground pool.
    40000L
    1.5 HP pump

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    reebok's Avatar
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    Re: sand/dead algea in bottom of pool?

    what does that mean? how did you shock?
    16x32 21,000 gallon in-ground exposed aggregate, 1.5hp pump, 120 sqft catridge filter, birdcage, solar panels, aquavac tigershark qc robot.

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    Re: sand/dead algea in bottom of pool?

    by adding 600g of hth shock powder all around the pool
    noon here now.. chlore maintaining at 2.5ppm
    just as the pump started , the entire bottom filled with a light dirty film.. after brushing it, it seems to have dispersed.... i am leaning towards a faulty filtration system after the sand was changed at the beginning of the season
    21' above ground pool.
    40000L
    1.5 HP pump

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    dmanb2b's Avatar
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    Re: sand/dead algea in bottom of pool?

    please post a full set of test results
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

    Pool School, TFTestKits, Pool Calculator

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    cubbybeave08's Avatar
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    Re: sand/dead algea in bottom of pool?

    Does it come back only on the bottom of the pool and only in the dips and divets in the liner? IF yes...it is dirt/dust or pollen from the air. Put a skimmer sock over your skimmer basket, and you will see that go away. You will see it all collect on your sock...But get that chlorine up to shock level...POOL SCHOOL! and get a good test kit
    Beave
    Aqua Leader 24ft Round AG Wil-Bar Influence w/54 inch walls 13,500 gallons
    Swimline J-Blue Opal Liner, 1 4X20 Fafco Solar Bear Solar Heater
    Hayward 2 HP Swim Pro Voyager Pump Micro 150 with 4 way timer
    Swim Pro Voyager Filtration System with Hayward ABS Pearl wide mouth skimmer

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    Re: sand/dead algea in bottom of pool?

    what about the bottom drain? is covering the skimmer basket really enough? does that mean the dust/pollen goes through the skimmer and is thrown into the water in the return line? why wouldn't this get picked up in the filter?

    these were the results from my latest water test at the pool store
    chlore: 3ppm
    ph: 7.2
    alcalinity: 100ppm
    hardness: 250ppm
    21' above ground pool.
    40000L
    1.5 HP pump

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    frustratedpoolmom's Avatar
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    Re: sand/dead algea in bottom of pool?

    You can rig a nylon stocking to fit over the return flow and see what is coming back thru the return, if it is a filtration issue.

    Sand filters, especially new sand, don't always filter the small stuff which is why we recommend skimmer socks and other "tricks" to improve filtration - like adding DE to the sand (instructions in pool school).

    I'd recommend you invest in your own test kit.

    Please take a moment to add your pool's specs to your signature. Go to User Control panel, then Profile, then Edit Signature.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: sand/dead algea in bottom of pool?

    Quote Originally Posted by frustratedpoolmom
    Sand filters, especially new sand, don't always filter the small stuff which is why we recommend skimmer socks and other "tricks" to improve filtration
    sock has been installed... can't tell yet if there is a improvement with the sock on
    how long before new sand in a fiter starts "to filter the small stuff"
    21' above ground pool.
    40000L
    1.5 HP pump

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    cubbybeave08's Avatar
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    Re: sand/dead algea in bottom of pool?

    Quote Originally Posted by helpmeplease
    Quote Originally Posted by frustratedpoolmom
    Sand filters, especially new sand, don't always filter the small stuff which is why we recommend skimmer socks and other "tricks" to improve filtration
    sock has been installed... can't tell yet if there is a improvement with the sock on
    how long before new sand in a fiter starts "to filter the small stuff"
    You should see a difference overnight. What kind of area do you live in? Are there lots of trees? Do you have farm fields nearby? In the spring and early summer I have a great deal of dust and pollen. Before I turn the pump on I can see it all floating on the surface of the pool. What happens is that if the pump is not running, it all eventually sinks. It is the same thing if you see a dark car in the summer it usually has a nice coat of dust on it. The pool acts in the same way. The waters surface traps any dust in the air...when it is really bad, I run my pump 24/7 with a sock in place. That really helps...It is like pealing lint off the trap in your drier.
    Beave
    Aqua Leader 24ft Round AG Wil-Bar Influence w/54 inch walls 13,500 gallons
    Swimline J-Blue Opal Liner, 1 4X20 Fafco Solar Bear Solar Heater
    Hayward 2 HP Swim Pro Voyager Pump Micro 150 with 4 way timer
    Swim Pro Voyager Filtration System with Hayward ABS Pearl wide mouth skimmer

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    DCAG's Avatar
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    Re: sand/dead algea in bottom of pool?

    Earlier in the season, our pool was a bit cloudy, so I added half a gal of bleach/day and ran the filter 24/7 for a few days. Which should have been bringing the FC up to about 4 ppm. No Help. I thought the bleach might be old, so I went and bought fresh bleach, and added 3 gal. Which would have brought FC up to ~15. The pool was crystal clear the next morning.

    You said it was slimy, so we'll assume it's algae for the moment, not filter sand...
    If your CYA was at 0 and you added 1.5 kg of CYA - that would be about right. (40 or so). 5 ppm FC would be good goal for you. (You really need to get a good CYA #, though.) Each time you've posted your Chlorine number it was less than 3 ppm. If your pool is 40000 litres, (we'll assume CYA of 40) try adding adding 10 litres of 6% bleach (normal, unscented). Run filter 24 hours.

    Also, after re-reading your previous comments, you could have a broken filter, AND algae. Tell us if the sock picks anything up. Also, don't put your test results in your signature.

    Dan
    16' X 24' Wilkes Pools "Genesis", 10K Gal
    Hayward Powerflo Matrix 1 hp, & 18" Pro Series sand (S180T)

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    Re: sand/dead algea in bottom of pool?

    Just backwashed and pressure guage was reading 20... after several minutes and alot of green stuff beeing backwashed through the looking glass valve, then rinsed the guage is now reading 18... backwashed some more and re-rinsed but the guage maintains a reading of around 18psi. When pump is off it reads 8psi and when the filter turns on it jumps right back to 18. Could this be of any help for diagnosing a possible filter failure?
    BTW, the surface water is clean and clear and I do live in a heavily wooded area.
    21' above ground pool.
    40000L
    1.5 HP pump

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