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Thread: Mustard Algae Just Won't Go Away

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    Smile Mustard Algae Just Won't Go Away

    Hi, new to the TFP site and forum. Nice forum...many thanks to all who participate.

    So, my overiding question is "Does HIGH CYA Cause Mustard Algae in what Otherwise Appears to be a Well Balanced Pool ?????

    In early June I went away for a week biz trip and got back to find a significant Mustard Algae Growth. I balanced and shocked before left as I always do...took the pH to around 7.2 and FC up to about 15+...I usually do this before I travel.

    Upon return it was pretty bad after only 7 days. Pool water looked like the green Gatorade, only a darker green. Yellow-green "dust" the color of Gulden's mustard on the walls and floor, especially the "shaded" side walls of the pool. So next morning I shocked heavily at sun up with 40-50 oz of 68% cal-hypo, brushed, filtered and back washed 3-4x during the day, added 32 oz of 60% PolyQuat Algecide at nightfall, and then took the pH down to 7.0 at about 10 PM. Filter ran night...thought about a floculent...but didn't add that. The pool water looked much better next morning. A lot of junk settled on the floor...Vacuumed what was on the floor to waste and thought I had "won"....as it was a major overnight improvement.

    Well...It just keeps coming back now about every three days. I'll get a thin coating of the yellow brown dust on the floor and less on the walls, vac to waste, and the next 2 days there it is again.

    During all this....I'll test the H20 often, 2x/day...typical numbers are pH around 7.4 - 7.6, I keep the FC up above 3, typically higher like 6. Cal 320, TA around 90.

    I think I figured out my problem....looking for some agreement here:
    I learned my CYA is 89. My kit does not test for CYA...

    I think I EITHER screwed up and put too much powdered stabilizer when I opened the pool in April when I was told it was close to CYA=ZERO by the pool store (probably false reading)
    OR the stabilized 3" tabs are adding too much CYA (or both).

    I'd like to hear some PRO opinions before I drain out 40% of my pool water to get CYA down to 40 ppm.

    Thanks..

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    Re: Mustard Algae Just Won't Go Away

    Welcome to the forum.

    I would not drain a quart of water until you can post your own, accurate test results. It is somewhat pointless to speculate without knowing where your parameters are and you can post them up.
    I'd like to hear some PRO opinions before I drain out 40% of my pool
    Straight talk for a minute.....the PROS are who got you where you are. What you should be looking for is learning to be independent from them and take charge of your own pool.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Mustard Algae Just Won't Go Away

    Thanks Dave...Copy that on the PROs.....I'll get some accurate readings as of today and post when I get them.
    I got the "89" reading on CYA from the local pool store.
    They provide a print out of all the readings. At the moment they are my only source to measure CYA.
    They said as long as I was below 100 my chlorine would work.
    I see from your chart that IF my CYA is High (I think it is) then I need much higher level of Cl than I had been typically using.
    I do think I'd like to buy the TF-100 kit.
    I have a Jack's Magic Professional Kit...uses the pill type reagents...but it does not measure CYA.
    Thanks!

  4. Back To Top    #4

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    Re: Mustard Algae Just Won't Go Away

    Still fighting the issue....

    So, I checked my numbers today as follows:

    • Pool Stats: 25K GAL, IG, plaster, new Hayward High Rate Sand filter, new Hayward 2.0 HP Single Speed Super Pump, Triton Propane Gas Heater
    • Water: well water, unfiltered, pool water about 83-85 degrees F, about 1-2 inches rain in last 7 days.
    • Pool is within 30 feet of several tall trees, lots more trees on 2 acre lot, no outdoor screen enclosure, southern MD
    • Test Results:

    FC - 6
    TC - 6.5
    pH - 7.5
    TA - 90
    CH - 320
    CYA - 89

    Did a vac to waste last night at 6 PM..... Ran filter for 4 hours thereafter.

    This morning at 7 AM I back-washed and there was some yellow-brown water seen in the filter view-glass for about 30 seconds. Then it cleared up...and I put it in Rinse mode for 20 sec, then back to normal Filter mode. Ran Filter.
    Water looks clear....The pool floor is homogeniously discolored with a light yelllow-brown tint. One or two places have a bit more accumulation, looking like yellow-brown dirt.
    I brushed the pool and there was a bit of yellow-brown "dust" coming up as the brush plowed thru it. Most of it is on the floor of the pool, but some on the walls, a bit more where the shaded side walls as the sun goes down are.
    The pool gets a little cloudy after complete brushing floor and walls, but not too bad. The junk seems to mix pretty quickly in to the clear water.

    Its almost 2 PM now...Filter has been running all day since 7 AM. Pool looks OK actually
    BUT!!!!
    Typically when I don't have time to brush for 1-2 days I'll come out seeing this same yellow-brown condition all over again.
    Longer gaps of 3-4 days with no brushing and the floor starts looking yellow-brown with a hint of green, even with the FC above 4.

    I am just looking to get the pool in a state where if I can't tend to it for 3-4 days due to business travel....it does not look yellow-green and I have a new mess when I return.


    Based upon the educational reading I have seen here in Pool School....I need to SLAM, then keep a higher FC given my high CYA (from the CYA-FC table for non-SWG pool). If/when I can get the CYA down by draining (ugh!!!) and refilling, then I am thinking the problem of the "yellow-brown algae dust" might just go away when keeping FC levels between 3-5. Hopefully the goal of having to

    Ordered a TF-100 kit also. Whoooo hoooo....

    Thoughts??? Thanks for your help!

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    borjis's Avatar
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    Re: Mustard Algae Just Won't Go Away

    sound right.

    I just went through a mustard algae slam myself. CYA was 70 so I held it mustard shock for days and it
    was finally defeated after 1 and a half weeks, brushing daily and running pump 24/7

    Afterwards my CYA was down to 35. chemgeek our resident chemistry expert said I likely had a rare
    condition where the mustard shock levels oxidized the CYA down. It doesn't always do that but
    it did happen in my water and I'm thankful as now the CYA is where it needs to be.
    16x32 IG Vinyl, 13,000 Gals. Hayward S-244T sand filter, SP2810X15 pump
    (1.5 HP motor) Raypak PR266AEN (266k btu) gas heater. TF-100 Test Kit.
    Dolphin E10 Cleaning Robot.

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    Re: Mustard Algae Just Won't Go Away

    So let's see .......
    - TF-100 on-order .. CHECK
    - Yellow-brown tint ... STAND-BY. Wait for TF-100 before assuming anything. It certainly may be algae/chemistry-related that will require a SLAM. But I'm also curious ... have you received any reports from your water district on the condition of your well water or if it containers any metals? You might like to do that now.
    - Drain - Yep, that's a possibility. But as Dave mentioned above, best to wait to confirm with YOUR OWN test kit if it truly is high or not.
    - Even if you do need to SLAM, you can't until you get your TF-100.

    For now, keep the water moving a bit, scrub areas to keep anything from sticking in any one place, and add bleach each evening just to keep things at bay. Soon you'll be armed with the TF-100 and in a much better position to take action.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Re: Mustard Algae Just Won't Go Away

    From your good description, you have algae in your pool and will need to SLAM it. Do not start the SLAM until you get the TF-100 kit.....it's impossible to SLAM correctly without it.

    DO NOT MAKE THIS MISTAKE.........Don't elevate your chlorine one time and then walk away disappointed when it doesn't work. Your chlorine must STAY elevated at SLAM value, perhaps for days.

    Follow the SLAM, ask for help, and we'll get your pool crystal clear....promise.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Mustard Algae Just Won't Go Away

    I am a believer. I had been doing exactly what you say.....elevating the CL in the pool once and walking away...Only to loose the battle over and over.
    I get it now. SLAM is the key. BBB method works. It is crystal clear (Pun intended!!)
    Will report back soon. Kit should be here today.

  9. Back To Top    #9

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    Re: Mustard Algae Just Won't Go Away

    Proud new owner of the TF-100 kit and testify that SLAM works. Pool is clear. Each day after I SLAMmed you could see less and less algae "dust" whrn you swept the pool floor...and less attached to the west side pool walls. So, now I just keep the FC at the proper level and I should be OK. Unfortunately our CYA is high, about 85.....and I understand this requires more CL use to keep the mustard algae away. We are going to do a complete tile remodel in August and saince that will require the pool to be drained 100%...I think I'll wait to drain/refill till then and be very very careful about keep the CYA below 50.

  10. Back To Top    #10

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    Re: Mustard Algae Just Won't Go Away

    UPDATE: it's a few days after I completed SLAM and I am in Maintain Mode...Checking FC daily and adding what the Pool Calc tells mne to add. It works. Pool has never looked better. Wife agrees. I now have the TF-100.
    Since I unfortunately have high CYA...I do understand I'll be spending a bit more on bleach in the near term......the good news is a tile restoration job is coming in early August....so they have to drain the pool anyway. I used the TF-100 to check my well water and it has a PH=7.4, CH = 170. So I should be good with that, but I plan to check for other things like copper/silver. After we refill the pool I am completely armed and dangerous now thanks to TFP site and won't let the "pros" at the pool store load me up with insidious chemicals that actually work at cross purposes one against the other. Thanks again.

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    Texas Splash's Avatar
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    Re: Mustard Algae Just Won't Go Away

    You're on your way! :ggodjob:
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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