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Thread: FC at level but still algae

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    FC at level but still algae

    I've been through pool school, bought the test kit, and thought i mastered it but still have algae creeping around.

    FC 5.5
    CC 0
    TC 5.5
    TA 140 (little high)
    CYA 60
    Ph 7.5
    12k pool vinyl liner


    i had the CYA issue at but turned my dark green swamp with live tadpoles into clear swimmable pool after about a week but now after keeping my free chlorine up to around 3-4 for the last month and its been fine. Last weekend, I noticed a touch of algae near the stairs and around the bottom edge near one of the jets - brushed it away and tested my levels and everything looked fine.

    However,, I hadnt been brushing like i should - could that be the problem? I did empty the cartridge filter after the shocking process and it was gross/white and hosed it all out.

    Today, I took my cartridge filter out and it was medium? green from algae. Could it possible that in the filter, algae somehow got in there and spreads to the pool even with high enough FC?.

    Also, my FC drops very quickly - i feel like i have to put more in like 5 gallons a week minimum to keep my FC at 5? Does that seem to high? I've tested my CYA like 5 times to make sure i'm doing it right - the black dot test and it comes in at 55-65. Maybe thats too high? PoolCalculator says 7 is my target FC so maybe i just need to get it there and keep it there.

    Any thoughts to my ramble?
    TEST KIT: Taylor Technologies K-2006C

    POOL: 33,000 gal 20'x40' IGP, Vinyl, 1.5 HP Two Stage Pump Motor, 340 sq.ft. Jandy CL340 Cartridge Filter, Jandy Aqua Pure PLC1400 SWG, Polaris 280, AquaLink RS By Jandy Control Center with Jandy PDA Model #8265

    JACUZZI: 320 gal Caldera Spa Paradise Series Martinique with OEM Aqua Sun Zone - XL-30AE Ozonator

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    Mod Squad jblizzle's Avatar
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    Re: FC at level but still algae

    You CYA is borderline too high. If you leave it, I would say that a FC of 5ppm is an absolute minimum. It sounds like you have been letting it drop below 5ppm (or I interpreted it wrong).

    The high use of FC and the visible algae means you need to go through the shock process again. After passing the 3 tests to stop, you have to be sure to never let FC below 5ppm. This may mean targeting 8ppm+ such that it is not below 5ppm the next time you test.

    Lack of brushing could certainly be a factor in areas of the pool with less circulation.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Mod Squad Bama Rambler's Avatar
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    Re: FC at level but still algae

    How long are you running the pump each day?
    How do you normally chlorinate?
    What type pool do you have?

    I suspect, as JB does, that it's not keeping the FC high enough and a bit of a circulation problem. Right now you need to perform the shock process to completion and then keep the FC up where it should be and brush any areas of less than adequate circulation.
    Dave J. TFP Moderator
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    Re: FC at level but still algae

    Did you complete the shock process by meeting all three criteria? If so, like they said above, you've somehow let FC drop too low and algae took back over.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
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    Re: FC at level but still algae

    Yes.. I run pump for 8 hours a day but I have this weird eco eztech variable motor that doesn't seem to work right. When I lower the speed, water doesn't flow very fast. Hard to explain but it doesn't fill up pump lid like it does on full speed.

    I'll try to lower my cya again a tad and keep my fc up after shocking. I did get it drop . It drops so fast sometimes and then my stabilizer was low so I added what calculator said and now it's high.

    TEST KIT: Taylor Technologies K-2006C

    POOL: 33,000 gal 20'x40' IGP, Vinyl, 1.5 HP Two Stage Pump Motor, 340 sq.ft. Jandy CL340 Cartridge Filter, Jandy Aqua Pure PLC1400 SWG, Polaris 280, AquaLink RS By Jandy Control Center with Jandy PDA Model #8265

    JACUZZI: 320 gal Caldera Spa Paradise Series Martinique with OEM Aqua Sun Zone - XL-30AE Ozonator

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    Re: FC at level but still algae

    It shouldn't drop fast after you finished the shock process, if you made it through to completion. If your OCLT was fine, your chlorine should be stable.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
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    Re: FC at level but still algae

    I meant fast after the fc levels were stable. My shock level was like 40 ..oops.. and then as I murdered the algae, it was around 10 then 8 then 5 all within a few day. I think I just have to check it more frequently and run my pump more. I let it dip too low when my stabilizer was low and maybe that allowed a little algae in.

    anyhow, I've learned a lot a pools from this forum. My pool was dark green couldn't see the steps with tadpoles swimming around to clear without having to go to the pool store.

    TEST KIT: Taylor Technologies K-2006C

    POOL: 33,000 gal 20'x40' IGP, Vinyl, 1.5 HP Two Stage Pump Motor, 340 sq.ft. Jandy CL340 Cartridge Filter, Jandy Aqua Pure PLC1400 SWG, Polaris 280, AquaLink RS By Jandy Control Center with Jandy PDA Model #8265

    JACUZZI: 320 gal Caldera Spa Paradise Series Martinique with OEM Aqua Sun Zone - XL-30AE Ozonator

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    Re: FC at level but still algae

    If you only did that one large chlorine addition, it is very possible you did not kill all the algae. You can't know until you perform the OCLT.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
    If TFP has helped you, please click to SUPPORT TFP!

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    Re: FC at level but still algae

    I'll do that thIs week... I may have to continue shocking.

    TEST KIT: Taylor Technologies K-2006C

    POOL: 33,000 gal 20'x40' IGP, Vinyl, 1.5 HP Two Stage Pump Motor, 340 sq.ft. Jandy CL340 Cartridge Filter, Jandy Aqua Pure PLC1400 SWG, Polaris 280, AquaLink RS By Jandy Control Center with Jandy PDA Model #8265

    JACUZZI: 320 gal Caldera Spa Paradise Series Martinique with OEM Aqua Sun Zone - XL-30AE Ozonator

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    Re: FC at level but still algae

    Bingo! Read through the shock process in Pool School, and post up if you have any questions! I've seen the shock process take up to a month before. It's not common, but it happens.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
    If TFP has helped you, please click to SUPPORT TFP!

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    Re: FC at level but still algae

    Quote Originally Posted by jblizzle
    You CYA is borderline too high. If you leave it, I would say that a FC of 5ppm is an absolute minimum. It sounds like you have been letting it drop below 5ppm (or I interpreted it wrong).

    The high use of FC and the visible algae means you need to go through the shock process again. After passing the 3 tests to stop, you have to be sure to never let FC below 5ppm. This may mean targeting 8ppm+ such that it is not below 5ppm the next time you test.

    Lack of brushing could certainly be a factor in areas of the pool with less circulation.
    Dumb question...

    If the target FC = 7 (pool school) should you aim to keep this as an absolute minimum? I may be wrong but in this case I would be typing 7 into the target in pool calculator after my nightly chlorine test then dosing the chlorine at night. Then the next day due to swimming and sunlight the level would drop below 7 and then top it up again every night?

    What I think you are saying in this post is best practice would be not let the FC level of your pool go below the recommended target value eg. 7?

    Or is it OK for your FC level to be gobbled up during the day and just top up to the target level at night, all other things going well?
    13,000 gallon; sand filter; inground; fibreglass; pump not sure yet (need to check); Installed over 12 months ago.

  12. Back To Top    #12
    Mod Squad jblizzle's Avatar
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    Re: FC at level but still algae

    Never let it get below the minimum listed in Pool School. If you typically lose 3ppm each day, then your target should be at least 8ppm if the min is 5ppm ... or higher to make sure it does not drop below the minimum.

    Posted from my Droid with Tapatalk ... sorry if my response is short
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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