Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 2 of 2

Thread: Memorize the CYA chart?

  1. Back To Top    #1
    DCAG's Avatar
    Join Date
    Jul 2009
    Merrimack, NH

    Memorize the CYA chart?

    I was just looking at the CYA chart.

    For the newbies, is it safe to remember the chart this way?

    1. To know your recommended FC take your CYA # remove the zero, and add 1
    2. To know your recommended shock level take your CYA # remove 0 multiply by 4

    Or is this how everyone remembers it, and I'm just catching on now?

    16' X 24' Wilkes Pools "Genesis", 10K Gal
    Hayward Powerflo Matrix 1 hp, & 18" Pro Series sand (S180T)

  2. Back To Top    #2

    Join Date
    Jan 2009
    Cupertino, CA

    Re: Memorize the CYA chart?

    Your shortcut certainly works for "normal" CYA ranges.

    If you look at Chem Geek's Chlorine/CYA chart (which the Pool School article is based on) the footnotes describe how the FC levels can be approximated by a percentage of the CYA level. Which is exactly what "remove 0 multiply by 4" calculates (i.e. times .4, or 40%), and reasonably close to what "remove 0 add 1" does.
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

Posting Permissions

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