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Thread: Low FC

  1. Back To Top    #1

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    Low FC

    Just looking for input.

    I didn't test yesterday but I just tested and my FC is low. It usually runs at 5-5.5, and that's at the lowest setting (20%) on my SWG. My results are

    FC 0.5
    CC 0
    PH 7.4
    TA 70
    CH 180
    CYA 35 (working on getting that up)

    So, that big dip in FC got my attention. I turned the filter back on, turned the SWG up to 40% and added 2 lbs of 65% Cal-Hypo. (Since my CH runs low, I keep that around for emergencies instead of bottled bleach.)

    I'm thinking that this happened because of a combination of the series of sunny days we've had and my husband leaving the hose in too long yesterday, replacing evaporation. The water was just below the arrows on the skimmer and when he took it out it was above the skimmer. Evaporation has brought it down to just below the top of the skimmer today. Our fill water is bland, no chlorine, 7.0 ph, no CH, no metals.

    If things aren't perfect with the water tomorrow I'm going to do a OCLT tomorrow night.

    Water LOOKS perfect.

    Would you recommend anything different?
    19,000 gallons, Well Water
    Stay-Rite System 3 Cartridge filter
    IG vinyl, MasterTemp 400 Propane heater
    Intellichlor 40 SWG, 2006 Taylor Test Kit with Speed Stirrer
    1.5 HP Pump

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    duraleigh's Avatar
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    Re: Low FC

    I think you have it completely under control....your grasp of pool water chemistry is good.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  3. Back To Top    #3

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    Re: Low FC - Update

    Ackkkkk....So in the light of day this morning I saw that there was actually VISIBLE green algae on one of my pool walls. OMG. I've never had that before. I've had cloudy water when opened in the spring and a couple of times over four years Ive suspected I was on the verge of a bloom. I am horrified.

    So, I added CL and I'm at FC= 18.5 and CC<.5. I've been brushing and brushing.

    Two questions:
    1. Any chance I'll pass the OCLT tonight? We have guests coming tomorrow and we'd like to let them swim.
    2. My hubby accidently knocked the scissors I was using to open the Cal-Hypo bags into the deep end. I can't brush right around them because I don't want to poke a hole in the liner. He plans on diving in to get them. Is it safe with CL at shock levels if he's only in for a few minutes?

    Thanks.
    19,000 gallons, Well Water
    Stay-Rite System 3 Cartridge filter
    IG vinyl, MasterTemp 400 Propane heater
    Intellichlor 40 SWG, 2006 Taylor Test Kit with Speed Stirrer
    1.5 HP Pump

  4. Back To Top    #4

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    Seacoast, NH
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    Re: Low FC

    Never mind about question two. He already went in an got them. Boys.
    19,000 gallons, Well Water
    Stay-Rite System 3 Cartridge filter
    IG vinyl, MasterTemp 400 Propane heater
    Intellichlor 40 SWG, 2006 Taylor Test Kit with Speed Stirrer
    1.5 HP Pump

  5. Back To Top    #5
    linen's Avatar
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    Twin Cities, MN
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    Re: Low FC - Update

    Quote Originally Posted by Deb04
    Ackkkkk....So in the light of day this morning I saw that there was actually VISIBLE green algae on one of my pool walls. OMG. I've never had that before. I've had cloudy water when opened in the spring and a couple of times over four years Ive suspected I was on the verge of a bloom. I am horrified.

    So, I added CL and I'm at FC= 18.5 and CC<.5. I've been brushing and brushing.

    Two questions:
    1. Any chance I'll pass the OCLT tonight? We have guests coming tomorrow and we'd like to let them swim.
    2. My hubby accidently knocked the scissors I was using to open the Cal-Hypo bags into the deep end. I can't brush right around them because I don't want to poke a hole in the liner. He plans on diving in to get them. Is it safe with CL at shock levels if he's only in for a few minutes?

    Thanks.
    Our guideline for safe swimming is up your FC shock level (depends on your cya), pool bottom clearly visible, and ph between 7.2-7.8. I also like CC <0.5 since some forms can cause eye and skin irritation. As for your husbands brief dive to retrieve the scissors, that should be fine.

    As for swimming tomorrow, keep your FC high now and redose hourly. Tonight, when you do the OCLT, check FC (and CC) a couple of hours after doing the evening test to see where you are, if you are still loosing FC at that point you can dose all night long to keep killing the algae. Then tomorrow just follow the guidelines above for safe swimming.

    Ohh, and brush, brush, brush often.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  6. Back To Top    #6

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    Re: Low FC

    Thanks.

    Water is starting to look a little cloudy. Dead algae? Should I turn off the filter for a hour to let the algae settle on the bottom (note I can see dead algae on the bottom) and then vacuum?

    I'm guessing that our solar cover now needs to be cleaned so my pool doesn't get reinfected. Any advice what to use to do that?

    BTW, FC dropped only 0.5 in the last hour. Fingers crossed.
    19,000 gallons, Well Water
    Stay-Rite System 3 Cartridge filter
    IG vinyl, MasterTemp 400 Propane heater
    Intellichlor 40 SWG, 2006 Taylor Test Kit with Speed Stirrer
    1.5 HP Pump

  7. Back To Top    #7
    linen's Avatar
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    Re: Low FC

    Unless your filter pressure is going up to fast to clean the cartridges quickly enough, I would leave it on filter for now and keep circulating. Clean the cartridge when ever the pressure goes up 25% from your clean filter pressure.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  8. Back To Top    #8

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    Re: Low FC

    The pressure isn't going up at all. The PB gave us (as in sold us without discussion for which I am very thankful) an oversized filter and an oversized SWG.
    19,000 gallons, Well Water
    Stay-Rite System 3 Cartridge filter
    IG vinyl, MasterTemp 400 Propane heater
    Intellichlor 40 SWG, 2006 Taylor Test Kit with Speed Stirrer
    1.5 HP Pump

  9. Back To Top    #9
    linen's Avatar
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    Re: Low FC

    Quote Originally Posted by Deb04
    The pressure isn't going up at all. The PB gave us (as in sold us without discussion for which I am very thankful) an oversized filter and an oversized SWG.
    Sounds good, just curious what size cartridge filter do you have?

    If you have algae that is pooling on the floor, I would vacuum it to waste if you can do that.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  10. Back To Top    #10

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    Re: Low FC

    Hmmmmm, not sure how to answer. Specs on the label:
    Sta-Rite system 3
    Model s7m120
    300 sq ft filtration area
    Rate 0.33 gpm/sq ft
    Max flow rate 100 gpm

    Does that answer?
    19,000 gallons, Well Water
    Stay-Rite System 3 Cartridge filter
    IG vinyl, MasterTemp 400 Propane heater
    Intellichlor 40 SWG, 2006 Taylor Test Kit with Speed Stirrer
    1.5 HP Pump

  11. Back To Top    #11
    linen's Avatar
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    Re: Low FC

    Quote Originally Posted by Deb04
    Hmmmmm, not sure how to answer. Specs on the label:
    Sta-Rite system 3
    Model s7m120
    300 sq ft filtration area
    Rate 0.33 gpm/sq ft
    Max flow rate 100 gpm

    Does that answer?
    Yep that answers it. Your cartridge filter is 300 sq. ft. and is right at the minimum we would recommend for you pool, so the good news is your set there
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  12. Back To Top    #12

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    Re: Low FC

    Surprised it's at the min. PB told us it was oversized. I certainly get his motivation to stretch the truth, but we have been able to go each summer with no rise in pressure. I believed PB because of this.
    19,000 gallons, Well Water
    Stay-Rite System 3 Cartridge filter
    IG vinyl, MasterTemp 400 Propane heater
    Intellichlor 40 SWG, 2006 Taylor Test Kit with Speed Stirrer
    1.5 HP Pump

  13. Back To Top    #13
    linen's Avatar
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    Re: Low FC

    No the PB was right compared to the rest of the industry, he doubled the size. Here we suggest double as a minimum....so you did right by him.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  14. Back To Top    #14

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    Re: Low FC

    Good to know that I'm still justified in thinking the world of our PB. I've recommended him to a lot of ppl.
    19,000 gallons, Well Water
    Stay-Rite System 3 Cartridge filter
    IG vinyl, MasterTemp 400 Propane heater
    Intellichlor 40 SWG, 2006 Taylor Test Kit with Speed Stirrer
    1.5 HP Pump

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