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Thread: Algae Problem in spite of good OCLT numbers

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    Apr 2011
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    Pensacola, Florida
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    Algae Problem in spite of good OCLT numbers

    I would like your opinion about my algae situation. I pass the OCLT (FC was 5 last night and 4.5 this morning), my water is clear, and my CC is 0. But I have algae on the walls and creases in places where my pool robot misses. Any suggestions? My current numbers are: FC 4.5, CC 0, pH 7.8, TA 90, CH 100, CYA 40.
    Here is some background. Mid April I SLAMed the pool. Then put Triclor in the feeder because we were going to be out of town for several weeks. When we came back we had some algae but we had also had tons of rain so I figured the chlorine just didn't keep up. So I shocked (not SLAM) the pool. All was well for a week and then the algae came back. So I guess I need to SLAM again but I don't understand why my numbers are spot on but I have algae.
    Pool: 18,000 gallons, Cartridge filter, In ground vinyl, Polaris pool cleaner

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    Mod Squad tim5055's Avatar
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    Re: Algae Problem in spite of good OCLT numbers

    Quote Originally Posted by jimcam22 View Post
    I would like your opinion about my algae situation. I pass the OCLT (FC was 5 last night and 4.5 this morning), my water is clear, and my CC is 0. But I have algae on the walls and creases in places where my pool robot misses. Any suggestions? My current numbers are: FC 4.5, CC 0, pH 7.8, TA 90, CH 100, CYA 40.
    Here is some background. Mid April I SLAMed the pool. Then put Triclor in the feeder because we were going to be out of town for several weeks. When we came back we had some algae but we had also had tons of rain so I figured the chlorine just didn't keep up. So I shocked (not SLAM) the pool. All was well for a week and then the algae came back. So I guess I need to SLAM again but I don't understand why my numbers are spot on but I have algae.
    If it as you describe, the water is not clear. Clear water means you see no visible algae.

    Shocking doesn't work Time to SLAM
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Azgirl71's Avatar
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    Re: Algae Problem in spite of good OCLT numbers

    I have to agree with Tim on this. Time to keep SLAMming and brushing.
    Lisa
    Intex AG vinyl 15' x 48" 4,300 gallons due to skimmer install, Krystal Clear SF pump combo 2800 GPH, Krystal Clear SWG, Pool Blaster Max vacuum, Hayward thru the wall skimmer, TF 100 test kit with speed stir, K 1766 Taylor salt test, My SLAM Process

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    Apr 2011
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    Pensacola, Florida
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    Re: Algae Problem in spite of good OCLT numbers

    Thanks. I will start SLAMing tonight. I have one quick question about the OCLT. When I am not in the slam process my filter does not run at night. So, independent of the slam process, does the filter need to be running when doing the overnight chlorine test or does it matter for accuracy. It was not running last night or this morning when I got my reading. Also, Lisa, I enjoyed reading your SLAM process. Very informative.
    Pool: 18,000 gallons, Cartridge filter, In ground vinyl, Polaris pool cleaner

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    JasonLion's Avatar
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    Re: Algae Problem in spite of good OCLT numbers

    As long as the pump is running for an hour after you last add chemicals, and half an hour before any water testing you are fine. There is no need for the pump to run all night.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    duraleigh's Avatar
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    Re: Algae Problem in spite of good OCLT numbers

    Guessing just a bit but it sounds like you may not be brushing enough. Algae can thrive down in cracks and hidey holes where the circulating chlorine cannot get to it. Unless you are already doing so, be sure to brush frequently during the SLAM and then make it part of your normal maintenance routine.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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