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Thread: Yellow algae destruction

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    Yellow algae destruction

    I am a new registrant but a 2 year follower. I love this internet resource! I recently used the pool calculator to SLAM my pool because of persistent small amounts visible yellow algae. Please don't question the diagnosis. I have a 18 x 36 vinyl lined pool, BBB. Before I SLAMed the pool I had the following pool chemistry: TFP kit FC 5
    TC 5
    CH 100
    CYA 60
    TA 120
    PH 7.6
    The pool calculator said to SLAM the pool for mustard algae I needed to reach 34 ppm. I added the calculated dose and ended up with 52 ppm. Does anyone know what might have happened?

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    mikemass's Avatar
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    Re: Yellow algae destruction

    Used a higher bleach %'age than you thought you were or miscalculated the size of you pool to be larger (volume-wise) than it actually is. Those are the 2 obvious simple places to start. Once rule them out we can dig deeper. Good news is - You probably won the game by catching Colonel Mustard in the Conservatory, with the lead pipe...... (or in the deep end with sodium hypochlorite as it pertains to this discussion)
    25 + year pool owner. Current pool (going on 11th year) - 38K gallon in ground Gunite/White Plaster, Spillover Spa, Hayward Cartridge Filter, Hayward 450k BTU NG Heater, Hayward Goldline Aqua Logic control with T-Cell-15 Salt Water Cell, Dolphin Explorer.
    You Need: Bleach, a A Test Kit & a Bookmark to "Pool School". Now what's your question?

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    kcindc's Avatar
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    Re: Yellow algae destruction

    What was your brand of chlorine, what the was %, and how much did you add?

    Manufacturers will produce bleach with higher concentrations listed because bleach looses it strength over time and when it is exposed to heat (like in shipping). It you got a really fresh batch, it could have been really strong.

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    • The type of filter you have (sand, DE, cartridge) and, if you know, the brand and model of the filter.
    • If you know, please tell us the brand and model of the pump, and mention if is it a two speed or variable speed pump.
    • Date of pool build/install, particularly important if less then a year old.
    • What kind/model of water test kit you are using
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    19K gal, IG vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot

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    Karen
    33K IG w spa plaster, Pentair 1HP Whisperflo, DE Filter, SWG CircuPool RJ-60, Dolphin Triton Plus, Raypak Dig 336K BTU, TF-100.
    Pool Math Chlorine / CYA Chart SLAM - Shock Level And Maintain
    2017 replaster/retile

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    Re: Yellow algae destruction

    Kcindc, I added 7.5 gallons of Walmart 10% "liquid pool chlorine". I didn't miscalculate the pool size. Thanks. I added the requested info to my signature.
    26700 gal. IG, vinyl, sand filter, Hayward mod sp2607x10 pump, 2006 install date, test kit TF-100, Polaris p955 cleaner, city water, no restrictions.

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    kcindc's Avatar
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    Re: Yellow algae destruction

    Thank you for entering your signature. It really helps us help you.

    Well, 7.54 jugs would raise you FC by 28 based on the size you listed. Your FC ended up double of what you expected. There are three possibilities or a combination thereof: a) your pool volume is less than you expect, b) the 10% is stronger than 10%, and c) testing error.

    Have you double checked your FC? When testing higher levels, it is important to do the test correctly. Letting the reagent sit, or taking to long to complete the test can cause an erroneous result. Are you using the speedstir? It helps with accuracy.

    Read here: Extended Test Kit Directions

    AS-DPD Chlorine Test
    FC and CC - Free Chlorine and Combined Chlorine

    Rinse the sample tube with pool water.
    Fill the sample tube with pool water to the 10 ml mark. The top of the sample will be curved. This curve is called a meniscus. The bottom of the meniscus should be level with the 10 ml mark.
    Using the small spoon shaped end of the dipper, add one heaping dipper, or two level dippers, of R-0870 and swirl to mix. If the sample turns pink for a moment and then turns clear again, or if it turns brown, add another dipper of R-0870. If the sample remains clear the entire time, your FC level is probably zero, however it is best to verify that with an OTO chlorine test, since the FAS-DPD test is prone to the occasional false zero.
    Swirling constantly and counting the number of drops as you go, add R-0871 one drop at a time. Continue adding drops until the color changes to clear. The pink color may become extremely faint before it goes away. Make sure that the sample goes completely clear.
    Multiply the number of drops by 0.5 to get your FC level.
    Add 5 drops of R-0003 and swirl to mix. If the sample remains clear, your CC level is zero.
    If the sample turns pink again, add R-0871 one drop at a time, swirling constantly and counting the number of drops as you go. Continue adding drops until the color changes to clear. The pink color may become extremely faint before it goes away. Make sure that the sample goes completely clear.
    Multiply the number of drops by 0.5 to get your CC level.
    Dispose of the sample safely. It is best to pour it down the drain with the water running. Do not add it back to the pool.
    Rinse the sample tube with tap water and store for next time.


    Notes
    Hold the dropper bottles vertically and squeeze gently, so that drops come out slowly and seem to hang on the tip of the dropper bottle for a moment before falling.
    The exact amount of R-0870 powder used is not critical. The goal is to add more than you really need rather than using too little. Using too little R-0870 powder can throw off the results of the test. You need to use enough to bind to all of the chlorine that is present. Adding extra, within reason, has no effect. At very high FC levels it is likely that you will need to use more than the normal amount.
    If left sitting on the counter, the sample will turn pink again one or two minutes after the test is completed. This is normal.
    When measuring high FC levels, or measuring FC when the CC level is relatively high, it is important to move through the test quickly. Drops should be added about once per second, or slightly faster, swirling the entire time. You can slow down a little at the end of the test, to give you time to watch for the end point.
    In rare cases the sample may turn cloudy. If this happens the test is still valid. You add drops until the sample turns cloudy white, i.e. the red/pink is completely gone, rather than waiting for it to turn clear.
    Any MPS in the water will count towards the FC reading. Taylor R-0867 Deox Reagent can be used to eliminate this interference.
    Over time, it is common for a cloudy residue to build up on sample tubes used for FAS-DPD chlorine testing. The residue can be removed by filling the sample tube with bleach, letting it sit for several minutes, rinsing, and then wiping throughly with a paper towel.
    There isn't normally any reason to do this, but if you need more precision you can do this test with a 25 ml sample of pool water and multiply the number of drops by 0.2. In most situations the added precision is useless and simply wastes reagent.
    R-0870 is DPD powder. The indicator in the powder turns pink when bound to chlorine. R-0870 powder gets darker over time and eventually starts to clump up. If it is clumped up, you should crush it back into a slightly lumpy powder before using it.
    R-0871 is FAS-DPD titrating reagent. It should be a clear colorless liquid. If it turns a dark yellow color, it has gone bad.
    R-0003 is DPD Reagent #3. It should be a clear colorless liquid. If it turns yellow, it has gone bad.
    The precision of the measurement is plus or minus one drop when up to 10 drops of titrant are used, or plus or minus 10% of the final reading, when more than 10 drops of titrant are used
    Karen
    33K IG w spa plaster, Pentair 1HP Whisperflo, DE Filter, SWG CircuPool RJ-60, Dolphin Triton Plus, Raypak Dig 336K BTU, TF-100.
    Pool Math Chlorine / CYA Chart SLAM - Shock Level And Maintain
    2017 replaster/retile

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    Re: Yellow algae destruction

    Thanks kcindc. I repeated the test twice. Once by diluting by half and multiplying by by 2. Same result. Chlorine liquid stronger than labeled most likely the culprit. Retested just now with fc of 34. Approx. 18 hrs in to SLAM. Should I be concerned with ph of 8.2 during a SLAM?
    26700 gal. IG, vinyl, sand filter, Hayward mod sp2607x10 pump, 2006 install date, test kit TF-100, Polaris p955 cleaner, city water, no restrictions.

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    mikemass's Avatar
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    Re: Yellow algae destruction

    Quote Originally Posted by Tpowel View Post
    Should I be concerned with ph of 8.2 during a SLAM?
    Likely inaccurate in a FC environment of 34 ppm. Unless that 8.2 is what you measured before the slam. Once you slam you aren't getting a true pH reading till it's over and FC levels come back to earth.
    25 + year pool owner. Current pool (going on 11th year) - 38K gallon in ground Gunite/White Plaster, Spillover Spa, Hayward Cartridge Filter, Hayward 450k BTU NG Heater, Hayward Goldline Aqua Logic control with T-Cell-15 Salt Water Cell, Dolphin Explorer.
    You Need: Bleach, a A Test Kit & a Bookmark to "Pool School". Now what's your question?

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    Re: Yellow algae destruction

    Thanks Mikemass. Ph was 7.6 before slam. Hopefully colonel mustard has been eliminated!
    26700 gal. IG, vinyl, sand filter, Hayward mod sp2607x10 pump, 2006 install date, test kit TF-100, Polaris p955 cleaner, city water, no restrictions.

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    kcindc's Avatar
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    Re: Yellow algae destruction

    FYI, city water contains FC. You shouldn't dilute the FC sample with city water.
    Karen
    33K IG w spa plaster, Pentair 1HP Whisperflo, DE Filter, SWG CircuPool RJ-60, Dolphin Triton Plus, Raypak Dig 336K BTU, TF-100.
    Pool Math Chlorine / CYA Chart SLAM - Shock Level And Maintain
    2017 replaster/retile

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