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Thread: White Mold/Sand change

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    Angry White Mold/Sand change

    We have been fighting white mold, we seem to get this every year for the past 3 or 4 years. Just completed a super 3-4x shock, scrubbing, added algicide silver at pool store recommendation. All water chem seems ok. Question I have is pool company switched to a red sand and it seems like this is when our white molds problem starts. Is it possible this could be the cause. Going to get new sand and pea gravel again today. Not sure what to get. Pool is almost clear. No new growth. Scrubbed all old away, have vacuumed, scooped and cleaned till exhausted.

    On on a side note I need to order a Mesh safety cover soon. To have to close pool. Want the most light blocking possible. Would prefer tan or black in color. Stock size, 18x36 rectangle with center 4x8 stairs. Would like 3x3 anchors. But could do 5x5. What is best suggestion. Trying to keep around $1k. I have searched and researched for days. Wish someone would make a checklist comparison chart for multiple brands.


    New new to forum. But not pool. It is about 32,000 gallons. Thanks in advance for any help.

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    Mod Squad YippeeSkippy's Avatar
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    Re: White Mold/Sand change

    Welcome to TFP

    I'm confused- did you toss in something called "shock" 3-4 times, or did you toss in 3-4 times the amount of something called "shock" ??
    Neither is how we recommend owners take care of the problem of algae.
    If you're having repeated problems there is something wrong with either your pool chemistry or the way you're chlorinating it.

    For treating algae we recommend a SLAM procedure--> Pool School - SLAM - Shock Level And Maintain

    We really need to have a full set of test results to advise
    My Amazon Smile for November12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Doheny Discovery Robot, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub.
    Our pool build--> Our Pool Solved Our Sloping Yard Skippy's Cheap Pool Cooler -->Skippy's New Fountain

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    Re: White Mold/Sand change

    Welcome to the forum.

    Your problem is not with the sand. It is with your water chemistry. Filters will NEVER clear a pool of living algae or mold and an algaecide is not very effective either.

    We can help you get your pool crystal clear and never have that issue again but you will have to do some homework. read "The ABC's of Pool Water Chemistry" up in Pool School. It's a good start and will hopefully lead you to asking your own questions and doing your own testing and stay out of the pool store.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: White Mold/Sand change

    If you maintain proper chlorine levels relative to the cyanuric acid level then white water mold is usually not able to take hold. You need to read the articles suggested in the Pool School, get yourself a proper test kit, the TFTestkits TF-100 or the Taylor K-2006 (see Test Kits Compared), post your results, and then we can figure out whether your CYA is too high and if that is the primary source of the problem (i.e. the FC too low for that CYA level).

    Also, please tell us what the actual product was that you used for your "3-4x shock". Typically, powdered shock products can make things worse (Dichlor increases CYA levels) or create new problems (Cal-Hypo increases CH levels).

    Because we don't know your true water chemistry values, we have no idea as to whether the best course of action is a partial drain/refill or whether you should start a SLAM. Everything begins with knowing what is going on with your pool water and to do that requires a proper test kit. Asking for help without a proper test kit is like going to the doctor but not doing any tests (no blood work, no scans, no stethoscope, etc.). We are trying to bring pool maintenance from the Dark Ages into the modern era, but we need your help. Please get yourself a proper test kit right away and give us the results.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: White Mold/Sand change

    My water test results are
    Calcium hardness 228
    Fc 15
    Total 15
    PH 7.4
    Alk 110
    TA 80
    Cya 100

    problem really got out of control when pump was down for over a week with motor repairs. Pool is vinyl. If that info helps.

    the reason I am replacing the sand is because there are layers of the mold in there where it has bound together. Some of them are an inch or more thick.

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    Re: White Mold/Sand change

    I also plan to purchase a new test kit as soon as I get to pool store for new sand.

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    Mod Squad YippeeSkippy's Avatar
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    Re: White Mold/Sand change

    The ONLY two test kits we recommend are the Taylor K-2006 (no other #, even if the store tries to sell you the 2005 claiming its the same. Its not) or the TF-100 from TFTestkits.net.

    Both tests are drop based and can test chlorine at up to 50 (yes, fifty!) ppm which is important when someone is dealing with an algae problem.
    My Amazon Smile for November12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Doheny Discovery Robot, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub.
    Our pool build--> Our Pool Solved Our Sloping Yard Skippy's Cheap Pool Cooler -->Skippy's New Fountain

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    Re: White Mold/Sand change

    I plan to purchase the K-2006

    Any opinion on if "red" sand is ok?

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    Mod Squad YippeeSkippy's Avatar
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    Re: White Mold/Sand change

    I've never heard of "red" sand. Its just important that it is pool sand and not play sand.
    My Amazon Smile for November12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Doheny Discovery Robot, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub.
    Our pool build--> Our Pool Solved Our Sloping Yard Skippy's Cheap Pool Cooler -->Skippy's New Fountain

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    Mod Squad kimkats's Avatar
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    Re: White Mold/Sand change

    Watch out for Quikcrete pool sand. We have a member that got some that was NOT pool sand even though it was labeled pool sand.

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: White Mold/Sand change

    The CYA of 100 ppm may mean that the actual level is far higher than that. The normal FC level was probably low (not 15 as currently measured) and this allowed white water mold to grow. So once you confirm your CYA level with your own good test kit (diluting the water as needed to be able to measure above 100 ppm CYA) then you'll likely need to do a partial drain/refill of water to lower your CYA level.

    As for the filter, it's possible to deep clean it following the instructions in this post and using Ahh-Some for filters. However, given that we don't know anything about this "red" sand it might be something to replace anyway. Up to you as to whether you want to try and get your sand filter in shape with its existing sand. Worst case you can try that and if it doesn't work then replace the sand.

    Is this Red Flint sand what you are talking about? It says it's a fairly fine sand at 0.45 to 0.55 mm (39 to 32 mesh) but their sieve analysis shows the 50% point being at around 26 or 27 mesh. This is in the normal range of 40 to 20 mesh for pool sand.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: White Mold/Sand change

    Well after a ton of research I have found out that what my pool store is calling "red" sand is actually Northern filter sand. They call it red because it is different colored than white silica sand.
    I am also kicking around the idea of switching to Zeobest Ultra...

    Here re is the link to the filter sand. Northern Filter Sand - NFM Pools

  13. Back To Top    #13

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    Re: White Mold/Sand change

    So that sand looks OK. I don't think the type of sand had anything to do with the white water mold. As for using a zeolite sand, you need to be careful because we've had mixed reports about them where some brands have been OK and some not. It has to do with the specific source of zeolite used. If not right, then you end up with a lot of sand getting blown into the pool so I suspect the issue is with the sand particle size. Zeobest Ultra doesn't list an effective particle size nor show a typical sieve analysis nor say that it is ANSI/NSF 61 Certified nor passed the AWWA Standard B100-09.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: White Mold/Sand change

    Ok so I got my new test kit....holy scientist... Lol. Here are results.
    FC 8.2
    CC 0.4
    TC 8.6
    PH 7.5
    Alk 160
    CH 340
    CYA 80

    Did end up buying white #20 silica pool sand and pea gravel. My filter is an older Tagelus TA-60. Pool installed in 1986
    manual recommends 70# pea gravel and 160-180 sand. Will pull top off of filter to see what is going on in filter tomorrow. I am sure there are issues as we have had sand in pool under jets and on ground from backwash hose for a long time. We replaced laterals and hub and stand last year to try to prevent sand but still have it. Also bought a new multivalve that we are putting on at same time. Hubby would like to make a huge flower pot at this time...lol

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