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Thread: Does Yellow OUT work

  1. #1
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    Default Does Yellow OUT work

    Help, please. I have been lucky enough to never have an algae problem til now: got that yellow "sand" which seems to brush off but reappears 8-24 hours later (on walls and where walls meet floor, etc. (IG 18000 gal, FC 2.0, Ph 7.6, Total Alk 80, CYA 50, Temp 86).

    I've been told this is likely mustard algae/pollen. Unfortunately, I sent someone else to the local Leslie's (in a panic) and they prescribed:
    a) bring PH up to 8.0
    b) Add Yellow Out + shock (they said my unstablizied chlorine (e.g., Sustain brand CalHypoChlorite would be fine)
    c) Wait a day, or two, vacuum and backwash and then restabilize PH (either let it drift over time or Muriatic acid)

    This sounded OK until I read the bottle of Yellow Out and it says it is NOT an algaecide. Did we get sold a (wrong) package of goods here?

    Thanks.
    -Marty

  2. #2
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    Default Re: Does Yellow OUT work

    Marty,

    I assume you are talking about this product. According to the MSDS, the product contains 100% "Disodium salt of ethylenediaminetetraacetic acid, dehydrate,Disodium sulfate" which is also known as EDTA which is a metal chelating agent. You are correct that this is not an algaecide.

    The instructions for Yellow Out have you first raise the pH above 8.0 (which could result in some cloudiness or scaling, depending on other water parameters). You then add 2 pounds of Yellow Out per 15,000 gallons. You then add Cal-Hypo or liquid chlorine (chlorinating liquid or bleach) to add about 10 ppm FC. You then circulate for 24 hours. Finally, you add another 10 ppm FC of chlorine.

    Their process is patented here where interestingly the patent is essentially using chlorine plus ammonia to form chloramine which is the primary decolorizing agent. I am going to guess, on the basis of this patent, that EDTA breaks down under higher levels of chlorine in alkaline (higher pH) conditions. I am guessing that they are using EDTA rather than ammonium sulfate in their product since they don't have to label the ingredients and it makes things less obvious.

    So basically this product just forms chloramine to kill the algae and then you add more chlorine to get rid of the chloramine.

    Of course, you could just shock with chlorine alone instead, but may need higher levels of chlorine due to higher CYA in the water. Using ammonia or bromine gets around the CYA issue by forming monochloramine or bromine that are not affected by CYA. It is not an approach promoted on this forum.

    As for your yellow/mustard algae, if that is what it is (rather than pollen), you need to shock at a high level and then maintain a higher FC than you are currently doing. 2 ppm FC with 50 ppm CYA is not sufficient. Ben's Best Guess CYA Chart requires a MINIMUM FC of 3 ppm with 50 ppm CYA. Unless you completely get rid of the yellow/mustard algae, even higher FC levels may need to be maintained, but certainly 2 ppm is not high enough. If the problem is pollen and not algae, then a skimmer sock is the way to go (or a pool cover).

    Richard

  3. #3
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    Default Re: Does Yellow OUT work

    Thanks for such a thorough reply, Richard. Due to imminent storm, and I need to leave town again in a couple of days, I went ahead and started the "treatment"....I'm finding that even though I've used a lot of chlorine (Cal Hypo) for shock, I am not getting a reading above just 2-3 PPM (normally, the amount of Cal Hypo I put in would give me 15 PPM)! I even threw in some Lithium Hypo! I did raise the PH first to 8.0 before adding the Yellow Out and the water is indeed a bit cloudy (from the Soda Ash). Would the Yellow Out (or the higher PH) cause a Taylor chlorine titration test to give false readings? (I would think not). I need to wait now til the storm is over (Hanna passing through later today), and see what the readings are tomorrow (e.g., FC and CC) to see what I minimally need to do before I leave on Monday (I *know* I need to vacuum and backwash before I leave). Do you suggest using acid to bring PH back down quickly from 8.0 or just let it drift...the groundwater Ph is 7.6, so I would expect the pool to get there without too much time (especially if I get a lot of rain today...they don't call it acid rain for nothin'!).

    Thanks again!
    -Marty

  4. #4
    chem geek is offline PF Support Team Whibble Konker chem geek 4 stars chem geek 4 stars chem geek 4 stars chem geek 4 stars
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    Default Re: Does Yellow OUT work

    The Yellow Out is using up the chlorine so that's why you get a low FC reading -- that is expected. I would also expect that your Combined Chlorine (CC) reading could be high during this period until you add more chlorine (which will get rid of the CC), but you don't do this right away..

    Since you've used this product, I would suggest following its directions which means after the Yellow Out and chlorine addition, wait 24 hours, then add more chlorine again to 10 ppm. That should get rid of any CC.

    At that point, you should be back to normal in the pool and can use Ben's chart as a guide and not let the FC get below 3 ppm FC with your 50 ppm CYA.

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