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Thread: Rust colored algae

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    Join Date
    Nov 2014
    Location
    Palm Desert, CA
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    99

    Rust colored algae

    Hello - My pool has been looking very good so far this year but I noticed some rust colored algae spots this morning.

    My testing from yesterday was:
    PH - 7.8
    TA - 70
    FC - 5.0
    CC - 0.5
    CYA - 70
    CH - 460
    Salt - 3000
    Temp - 92
    CSI - 0.13

    We are now in the 100's with this weekend being 114 and 113 degrees. Do I need to up the FC and CYA a little now we are in the heat of summer out here (my SWG is programmed to 50% output). ?

    I have some Leslies Fresh and Clear (fast acting non-chlorine oxidizing shock). Would that be good to use to speed up getting rid of the algae? I think it's algae since our water has no copper, etc in it and I also had this rust type spot last year.

    Also, now that we are using the pool our normally zero CC has been 0.5. Is Pool Perfect plus Phos Free the right product to lower this down? I have a few bottles left from last summer.

    Thanks! Lisa
    17,000 gallon inground pool; Plaster redone January 2015; Pentair Cartridge Filter; SWG; Age of pool unknown (house built in 1973); Taylor K-2006 Test Kit.; Doheny Discovery robot cleaner.

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    Texas Splash's Avatar
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    Re: Rust colored algae

    Hi Lisa! Without question, do NOT put any of those pool store products into your pool. Yuck! IF you suspect algae like you did last year, then implement a "SLAM". Don't try to raise your CYA any more right now. But perhaps add enough acid to bring your PH down to about 7.2 before starting the SLAM.
    Your SLAM "FC" level would be a 28, so you need to use the Poolmath calculator to make sure you get enough bleach in there to keep it at the level and "Maintain" it until you pass all 3 SLAM criteria:
    1. Water is clear
    2. You do not lose any more than 1ppm of FC overnight (that's the OCLT)
    3. CC (Combined Chlorine) is <.5
    At the same time, continue to run your pump 24/7. Remove any “muck” and debris, scrub all parts of your pool to expose any algae, and vacuum/clean (or backwash) filter as necessary. You may have to do this several times. It's a lot of babysitting, but with patience and consistency, you will succeed.
    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.
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  3. Back To Top    #3
    DaninFLA's Avatar
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    Apr 2015
    Location
    Sarasota, FL
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    Re: Rust colored algae

    your FC looks good for your CYA, but if you have Algae, you need to SLAM. most likely your FC fell below minimum at some point. if you have algae, you need to SLAM and with your CYA level, your SLAM level is 28.

    don't add any phos free or anything other than chlorine/bleach.

    are you familiar with the SLAM process??
    Dan
    9,000 gallon in-ground Saltwater pool, plaster, cartridge filer, 1.0 hp pump, Hayward T-15 SWCG, TF-100
    Pool School - Chlorine / CYA Chart; Pool School - Test Kits Compared;

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    Texas Splash's Avatar
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    Re: Rust colored algae

    Also, while we always encourage pool owners to do their own testing (like you do with the K2006), about the only test we will support at the pool store is having them check your water for metals. So if you wanted, you could have them do a test, and just ignore everything they have to say except for iron/copper. Just a thought.
    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!

  5. Back To Top    #5

    Join Date
    Nov 2014
    Location
    Palm Desert, CA
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    99

    Re: Rust colored algae

    Thanks everyone! One more question, we are going out of town for the next few days. Is it ok to wait until Friday to start the SLAM? Since our PH rises due to the new plaster we did in January we add acid daily, so I was actually going to try to take that down to 7.2 to last the 3 days until we are home. Any problems with that or starting SLAM in a few days instead of immediately?

    FYI - we did have the pool store test our water a few months ago and there are no copper/iron in it so I really think this is some sort of algae. It's palm tree trimming time too and all the debris keeps falling in the pool. If I remember correctly this was about the same time as last year when the rust colored spots appeared so maybe it's related to that.
    17,000 gallon inground pool; Plaster redone January 2015; Pentair Cartridge Filter; SWG; Age of pool unknown (house built in 1973); Taylor K-2006 Test Kit.; Doheny Discovery robot cleaner.

  6. Back To Top    #6
    Texas Splash's Avatar
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    Re: Rust colored algae

    I suspect you should be okay on metals then and can focus on algae. No sense starting a SLAM now though if you can't maintain it while you're gone. So I would say "sure", start it when you get back. Have a nice trip. Pool will be there when you get back, and so will we.
    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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