Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 9 of 9

Thread: When is FC too high to go in the pool?

  1. Back To Top    #1

    Join Date
    Oct 2007
    Location
    Indianapolis, IN
    Posts
    9

    When is FC too high to go in the pool?

    We just had our pool built last fall and used it for just two months. The builder opened it for us a week ago and shocked it. The FC is 14ppm and CC 0. My kids have been bugging me to go in even though it has been pretty cool here in Indianapolis.

    I have searched the internet and this forum but have been unable to find an answer to my question about when is FC low enough for us to swim. It has been cool here and we have been away during the day so I have not had much chance to leave the pool open to release more chlorine.

    Thanks for all the information here. I plan on using the chlorine pucks the pool builder has given to me until I don't want my CYA to go up any further and then switching to bleach--CYA is at 30 right now. I also started adding acid last year because my TA was well over 200. It is now down to 180 and I'll keep working on that. I have not even tested PH yet because FC is so high. I have a vinyl liner pool.

    Mark
    22K gallon vinyl IG, 1 HP Hayward SuperPump, 24" Hayward S244T sand filter, RayPak P-206A-EN-C gas heater, Pentair Rainbow 320 chlorine feeder (only used when away from home), Use BBB method.

  2. Back To Top    #2
    Mod Squad JohnT's Avatar
    Join Date
    Apr 2007
    Location
    SW Indiana
    Posts
    8,721
    With CYA of 30, as sunny as it is today you ought to lose a good bit. I'd probably swim at that level, but in an old bathing suit.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

  3. Back To Top    #3

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,085
    14 ppm FC with 30 ppm CYA is technically equivalent to 0.8 ppm FC with no CYA so not that different than many indoor swimming pools. As John says, take an old swim suit, but you should be fine (and don't drink the water in volume -- not that you would). Even if you were off on the CYA test and it was really 20 ppm, that's still equivalent to around 1.8 ppm FC with no CYA so not a problem.

    Remember that the secret for lowering the TA is aeration while having the pool at a lower pH. If you lower the pH somewhat, you can have your kids splash in the pool for aeration (but with them in the pool I wouldn't lower the pH too much -- not lower than 7.2).

    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"

  4. Back To Top    #4
    Guest
    As a general rule of thumb ( based on what many state health departments consider safe for commercial pools and spas), anything under 10 ppm with normal CYA levels should cause no problems at all.

  5. Back To Top    #5

    Join Date
    Apr 2008
    Location
    Indonesia
    Posts
    311
    I am wondering about the CYA/Chlorine relationship.

    With higher level of CYA, the effective free chlorine becomes lower or less effective but its more stable. Understood that.
    We know that chlorine is an oxidizer and sanitizer, so in high concentration is not good.

    Now..... assuming I have a free chlorine level that is 20ppm but has high CYA level that makes it equivalent to 3.0 FC (assumed ). In real life scenario if I swim in my pool, will the effect to me as a person is the same as having a 3.0PPM FC or the 30PPM FC ? The abundant power of 20PPM free chlorine to oxidize is there.... right, its just the CYA "hugging" it down. Hugging is not neutralizing right ? Man.... this chemistry is so magical for me....


    Thanks
    SPP
    35,000 GL pool. In Ground. Concrete with all white ceramic tiles. Outdoor but shaded.
    Approx 36 ft by 15 feet. 2HP Hayward Super Pump, Hayward Sand Filter with Zelbrite ( Zeolite ), Hayward Cartridge Filter, Aquamatic Silver+Copper Ionizer ( suspended use since Oct 2008 ), Prozone Ozonator, 2 gram/hr, Analog Flowmeter on pipe

    Back Up Pump & Filter on trolley, Pentair 1.5HP + Pentair Cartridge Filter, Slime Bag 1 micron Jumbo Size, downstream of Cartridge

  6. Back To Top    #6
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879
    CYA binds to the chlorine and prevents it from reacting. The process is reversible, as the active chlorine level goes down the CYA unbonds and releases more active chlorine.
    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

  7. Back To Top    #7

    Join Date
    Apr 2008
    Location
    Indonesia
    Posts
    311
    Thanks Jason. I am learning more each day.
    35,000 GL pool. In Ground. Concrete with all white ceramic tiles. Outdoor but shaded.
    Approx 36 ft by 15 feet. 2HP Hayward Super Pump, Hayward Sand Filter with Zelbrite ( Zeolite ), Hayward Cartridge Filter, Aquamatic Silver+Copper Ionizer ( suspended use since Oct 2008 ), Prozone Ozonator, 2 gram/hr, Analog Flowmeter on pipe

    Back Up Pump & Filter on trolley, Pentair 1.5HP + Pentair Cartridge Filter, Slime Bag 1 micron Jumbo Size, downstream of Cartridge

  8. Back To Top    #8
    Guest
    The FC combines with the CYA to form chlorinated isocyanurates. Think of them as a very special kind of combined chlorine, which they are. They do not have the sanitizing power or oxidizng power of hypochlorous acid, our normal FC.
    The more CYA in the water the more that can combine with the added chlorine to form chlorinated isocyanurates.
    This is why you need higher FC levels when the CYA levels are high.
    The interesting thing about chlorinated isocyanurates is that they test as FC on DPD and FAS-DPD testing.

  9. Back To Top    #9

    Join Date
    Apr 2008
    Location
    Indonesia
    Posts
    311
    Amazing....Thanks bear.
    I have always hate chemistry in school...but i like learning about pool chemistry now... :P
    35,000 GL pool. In Ground. Concrete with all white ceramic tiles. Outdoor but shaded.
    Approx 36 ft by 15 feet. 2HP Hayward Super Pump, Hayward Sand Filter with Zelbrite ( Zeolite ), Hayward Cartridge Filter, Aquamatic Silver+Copper Ionizer ( suspended use since Oct 2008 ), Prozone Ozonator, 2 gram/hr, Analog Flowmeter on pipe

    Back Up Pump & Filter on trolley, Pentair 1.5HP + Pentair Cartridge Filter, Slime Bag 1 micron Jumbo Size, downstream of Cartridge

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •