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Thread: Can't figure this one out, good levels but getting algae

  1. Back To Top    #1
    copotay's Avatar
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    Aug 2011
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    Lafayette, La
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    Can't figure this one out, good levels but getting algae

    Been successfully using the BBB method with my new pool build this year up until now.

    FC = 4 - 9 - usually 3-4 at end of day, and bring it to 9 at night currently
    TC = 4 - 9
    CC = 0.0
    PH = 7.6
    TA = 120
    CH = 90
    CYA = 50
    Temp 90 - 92

    Over the last few weeks I was keeping the FC at 6 or 7 with a daily loss to about 2 or 3 until our temps here in south Louisiana began rising above 90 and the pool water temps went up about two weeks ago after a week long period of 1/2 rains daily that finally stopped. Started seeing what looks like greenish algae blotches beginning to form along the coves and near where a few wrinkles are in the liner. So I shocked for two days, (calculator shock level 16 - 17), after vacumming to waste all the green splotches, keeping the level up then let it come down to 9 and kept it there with a daily loss of about 4 maybe 5.

    I have about 10 - 11 hours direct sun and heat indexes in the upper 100s. The pool does not really cool off at night when the temp stays in the lower 80s and heat index remains about 90 at night.

    I have been targeting to 9, but after two days the botches returned. So I brought it up to 9 last night again before dark, scrubbing the blotches clean before adding the bleach. Did the overnight test, testing it this morning before the sun hit it, and I got 8.5 showing only a 0.5 overnight loss. I know you normally overnight test during shocking, but I wanted to see how much I lost during a normal run. I cannot figure out why these botches keep returning after a day or so. I am using the FASDPD test for accuracy.

    This has been repeated over the last two weeks twice.

    The local pool experts are advising that everyone around the area has been having problems with algae reforming even two or three days after shocking even with high levels of bleach due to our past heavy rains and extreme heat. I have inspected the blotches during vacumming under the water up close with scuba mask and it appears to be the regular old green algae that "poofs" when you disturb it. It does not look like mustard with the pictures I have seen with the greenish/yellowish/brownish tint. The water is relatively clear for the most part with some slight haze to it. I have bleach scrubbed all floats, washed bathing suits, and scrubbed the ladder/walls. I had my pump to run on 12 hours from 9:00 am to 9:00 pm and just started running it 24 hours straight, but it reappears. My one jet is pointed outwards away from the return and can see with floating objects that circulation appears to be correct, causing most debris to settle directly in the middle of the pool.

    Are my numbers correct in anyones opinion, am I doing something wrong or is it just the extreme weather, is anyone else having a similar problem?
    21 X 52 Sharkline Venture, 10,400 Gallons,
    Hayward Pro Series 18 Sand Filter, BBB Method, Leslies DPD Complete Chlorine Kit, Taylor K-1515-A - Drop Test, FAS-DPD Chlorine

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    Join Date
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    Location
    Greentown, IN
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    Re: Can't figure this one out, good levels but getting algae

    You need to read through pool school and "how to shock".. It sounds like you haven't really gone through the entire shock process, and with a cya of 50 your FC should never be below 4 after you've completed the shocking.

    Your pump needs to run 24/7 until you have passed all of the tests of pool shocking.

    Get your chlorine up to recommended shock value for your pool, use the pool calculator.
    Maintain that level until your ...
    1) Water is clear
    2) You have no CC
    3) You lose no FC overnight.

    While you are shocking .... brush the pool daily. Back-wash as needed. Run that pump and filter.

    After you've met all the criteria.... Keep that chlorine level in check or you will be doing the shock process again!
    Indiana, ABG 24'x52" Galveston by Blue Cascade (Craigslist buy w/part of deck included), 13,500 gallons, Intex SWG, solar panels mix 2, TF-100 test kit.

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    frogabog's Avatar
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    Re: Can't figure this one out, good levels but getting algae

    Actually, it sounds like the OP has done everything correctly. However, at 50ppm if you take a look at the CYA/Chlorine chart in pool school shock level is 20ppm. I think this might be a case where deferring to the chart vs the calculator might solve the problem.

    At 30ppm CYA and below, the pool calculator is more aggressive. Above that, the shock levels are considerably higher each increase in CYA. Typically both work at any CYA level, but when the lower level is used correctly and algae is continuing to bloom using the higher shock level (either way, calc or chart) is the next step.

    I'd shock at the chart level of 20ppm, and perhaps even a bit higher so it doesn't fall below 20 while shocking. See what that does.
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

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    copotay's Avatar
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    Aug 2011
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    Lafayette, La
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    Re: Can't figure this one out, good levels but getting algae

    Tks for the comments and that could be it frogabog, going up on the shock level, I assumed the calculator was giving me the correct shock number. I will give it a go and see if that will cure the patches.
    21 X 52 Sharkline Venture, 10,400 Gallons,
    Hayward Pro Series 18 Sand Filter, BBB Method, Leslies DPD Complete Chlorine Kit, Taylor K-1515-A - Drop Test, FAS-DPD Chlorine

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