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Thread: Pool seems crisp as long as the HOCI is above .05 ppm

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    Join Date
    Jun 2007
    Location
    Atlanta, GA
    Posts
    71

    Pool seems crisp as long as the HOCI is above .05 ppm

    It seems that when I shock my pool, it looks fresh and crisp. As the FC drops to normal levels, it crosses some threshold and loses it's crisp look. I'm guessing that line is .05 HOCI, because after my pool dropped below 10ppm FC, that's when I noticed it wasn't as crisp. The spreadsheet says I need 9ppm FC to get .05 HOCI. I'm going to push my chlorine back up to 9ppm and see what happens. What do you think? Could this be an algae problem still? I just brushed my pool, like I do every weekend. This time, there was some brown dust that would brush up in many places.

    FC 6
    PH 7.4
    CA 370
    CYA 80
    Temp 85
    Borates 50
    Phosephates 1000+
    Location: Atlanta, Georgia.
    Pool: 15,000 gallon 32'x18', 3'-6' deep in-ground gunite pool, Sta-Rite 3 125 GPM 2-filter cartrige, 1.5 HP Sta-Rite pump, solar heater, Goldline SWG, Jandy controls, opaque automatic CoverStar solar pool cover, 3 waterfalls (not from spa).
    Spa: 485 gallon in-ground square acrylic over fiberglass suspended over gunite Sunset brand spa, isolated system, natural gas heater, 2-speed (4hp/11hp) main pump, 3hp booster pump, chlorine sanitized.

    To my pool store owner, nothing is more important than my pool and my money.

    Richard's PoolEquations Spreadsheet

  2. Back To Top    #2

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,085
    Every pool is a little different. In my pool, the "crisp" threshold appears to be around 0.02 ppm HOCl (or maybe 0.03) but since you've got lots of phosphates in your water, maybe 0.05 is the threshold for your pool. The 0.05 is roughly the mid-point in Ben's original table so probably works for most pools. We know that yellow/mustard algae needs higher chlorine to keep away -- about the 0.07 column. So perhaps in your pool you'll need to keep the chlorine at the 0.05 level.

    As for whether you still have algae trying to bloom, you can see the overnight drop in the FC level. Chlorine consumption and "crisp" vs. dull water can be not only from algae, but from particulate matter. Not only will higher chlorine break some of that down faster, but longer filtration or better filtration (i.e. some DE added to a sand filter) might help. Anyway, those are some things to try.

    Richard
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

  3. Back To Top    #3

    Join Date
    Jun 2007
    Location
    Atlanta, GA
    Posts
    71
    Should I add something to try to reduce my phosphate levels?
    Location: Atlanta, Georgia.
    Pool: 15,000 gallon 32'x18', 3'-6' deep in-ground gunite pool, Sta-Rite 3 125 GPM 2-filter cartrige, 1.5 HP Sta-Rite pump, solar heater, Goldline SWG, Jandy controls, opaque automatic CoverStar solar pool cover, 3 waterfalls (not from spa).
    Spa: 485 gallon in-ground square acrylic over fiberglass suspended over gunite Sunset brand spa, isolated system, natural gas heater, 2-speed (4hp/11hp) main pump, 3hp booster pump, chlorine sanitized.

    To my pool store owner, nothing is more important than my pool and my money.

    Richard's PoolEquations Spreadsheet

  4. Back To Top    #4
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,887
    I doubt it has anything to do with the phosphates. Have you tried checking for chlorine loss overnight?
    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

  5. Back To Top    #5
    gonefishin's Avatar
    Join Date
    Apr 2007
    Location
    Joliet, Il.
    Posts
    389
    I agree with the others suggestion to check your overnight FC levels. Instead of shocking your pool water up to a certain level and then letting it drop, shock up to that level and sustain that level until your free chlorine levels hold overnight.

    dan
    21' Aqua-Leader AGP (10,200 gallons).
    Hayward cartridge filter and two speed pump.
    Aqua-Cal HeatWave 100k (HeatPump)
    Salt 3200ppm (in non-salt water pool)
    Borates 20ppm (slowly raising)
    Aqua-Rite SWG

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