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Thread: Grrr.....something chewing my FC

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    Grrr.....something chewing my FC

    Ok. I opened my pool to a lovely green algae habitat. I brushed, vacuumed, and SLAMMED my way to a beautiful clear pool. I went on vacation for 8 days, brought up to shock level, added 5x3" tabs to chlorinator and came back to a clear pool but FC was around 3. My CYA is 50-55. I brought the FC up to above target level (seeing that no one is swimming in it yet) around 10 or so for the last week. Now all of a sudden my FC is getting chewed up fast. I did an OCLT last night and went from 13 to 9.5 so I brought the FC level to 25-30, and just did a FAS DPD this afternoon and im at 13.5. I have questions on how everyone else does this. I test before I add bleach, then add approximately what I am supposed to, but I don't retest to make sure it is at the level I want. Seems that I would use a 10gm DPD powder in just a few days if I did that. The water is crystal clear....the usual stray leaves and 30-40 insects in the bottom. I am only able to shock the pool about 3 times daily due to time constraints. Am I growing something good in my pool that I just can't see? Do I keep plunging the bleach in? My pool gets sun from 7am-8pm so I keep my CYA a little higher. I went ahead and purchased a 113gm jar of dpd powder that should be here in about a week. Any suggestions? Am I even doing this right? Is it better to add the bleach in the evening so it has more time to work before being burned off? Thanks in advance for any help
    Complete results:
    FC 13.5
    CC 0
    pH 7.2
    Alk 110
    CYA 50-55
    12,000 gal Octagon vinyl in-ground pool. Hayward S220 sand filter 3/4 hp pump, heat pump heater

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    Re: Grrr.....something chewing my FC

    side note - just added 121oz of 8.25% bleach that should bring FC up to 22
    12,000 gal Octagon vinyl in-ground pool. Hayward S220 sand filter 3/4 hp pump, heat pump heater

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    Mod Squad woodyp's Avatar
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    Re: Grrr.....something chewing my FC

    Did you pass the OCLT on your first pre-vacation SLAM?
    16x32x52" Steel Cornelius Miramar AGP Vinyl liner 13,100 gal. Buried 2 ft.
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    Re: Grrr.....something chewing my FC

    I believe I did but I'm not totally sure. I have a hard time remembering what I had for breakfast today. You think maybe I hadn't gotten all the algae out and it bloomed over vacation? The pool is crystal clear...not that it's any indicator
    12,000 gal Octagon vinyl in-ground pool. Hayward S220 sand filter 3/4 hp pump, heat pump heater

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    Mod Squad woodyp's Avatar
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    Re: Grrr.....something chewing my FC

    Well, if it wasn't completely "cured".....and the doctor (you!)...was out for a week and the FC got low, I'd suspect that.
    16x32x52" Steel Cornelius Miramar AGP Vinyl liner 13,100 gal. Buried 2 ft.
    2 Speed Hayward Power-Flo Matrix 85 g.p.m. 22" 250lb. sand filter hard plumbed
    Pool Rover Jr., Pool Blaster Max, Diver Dave TF100 Test Kit/Speed Stir
    Margaritaville Frozen Concoction Maker, Liqour Chiller, & Drink Mixer & Party Tub----Collect 'um all!

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    Re: Grrr.....something chewing my FC

    So i should bring up to shock level like 3 times per day until I pass the OCLT test? That's gonna burn up my dpd powder quick. But if it's what I have to do then it is what it is.
    12,000 gal Octagon vinyl in-ground pool. Hayward S220 sand filter 3/4 hp pump, heat pump heater

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    Re: Grrr.....something chewing my FC

    I test before I add bleach, then add approximately what I am supposed to, but I don't retest to make sure it is at the level I want. Seems that I would use a 10gm DPD powder in just a few days if I did that
    I see no reason for most folks to re-test after you calulate the correct dosage. That said, many do just for the reassurance.

    On just a slightly different subject, do not conserve your powder so much that you are afraid to test. Order some more......this forum is based on precision testing to provide you the knowledge you need.

    The powder is less than $10 and you will spend 5 times that much SLAMming your pool with bleach if you let your FC dip too low.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Mod Squad woodyp's Avatar
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    Re: Grrr.....something chewing my FC

    dpd powder-------is cheaper than bleach------------is cheaper than your time,---------- having to guess at maintaining that SLAM level and for longer periods of time.
    16x32x52" Steel Cornelius Miramar AGP Vinyl liner 13,100 gal. Buried 2 ft.
    2 Speed Hayward Power-Flo Matrix 85 g.p.m. 22" 250lb. sand filter hard plumbed
    Pool Rover Jr., Pool Blaster Max, Diver Dave TF100 Test Kit/Speed Stir
    Margaritaville Frozen Concoction Maker, Liqour Chiller, & Drink Mixer & Party Tub----Collect 'um all!

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    Smykowski's Avatar
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    Re: Grrr.....something chewing my FC

    Only way to tell for sure is to do an OCLT.

    I think you may just be seeing higher FC consumption due to the higher air/water temps. Could that be the case?
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
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