Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 4 of 4

Thread: Chlorine/CYA Chart

  1. Back To Top    #1

    Join Date
    Apr 2009
    Location
    Orange Park, FL
    Posts
    104

    Chlorine/CYA Chart

    In the 60-80 CYA range, why are the Minimun and Target FC ranges much lower for SWGs than non-SWG pools? I've only had my SWG 2 weeks, but I'm getting algae at the lower target range. I'm in NE Florida and we've been getting monsoon rains and perhaps that is influencing the water balance.
    15x30 IG vinyl liner pool, pool cage
    Hayward S-220T high rate sand filter and Hayward super pump w/1hp motor
    Hayward SwimPure Plus SWG
    Polaris 380 cleaner and booster pump

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,887

    Re: Chlorine/CYA Chart

    The FC levels for SWGs have been determined by trial and error. They appear to work for most people. We don't know why the level is lower for SWG pools than for other pools, all we know is that it works. I have heard a couple of different theories, but none of them are completely convincing.

    Some pools require higher FC levels than the minimum that appears in the chart. That is why we express it as a range, between the minimum and the target levels. Also, keep in mind that you should test the water in the early evening, which is when the FC level is normally lowest, to be sure you are not going below the minimum at that time.

    When you have large storms, it is easy for your FC level to go below the minimum for a while during the storm. if that happens, you can get algae at that time. SWGs tend to fight with algae, such that the algae never really gets going but also never really takes over. You need to make sure the algae is completely killed, by carefully shocking your pool, before you go down to the low end of the recommended range.
    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

  3. Back To Top    #3

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,085

    Re: Chlorine/CYA Chart

    Quote Originally Posted by jagfan
    In the 60-80 CYA range, why are the Minimun and Target FC ranges much lower for SWGs than non-SWG pools? I've only had my SWG 2 weeks, but I'm getting algae at the lower target range. I'm in NE Florida and we've been getting monsoon rains and perhaps that is influencing the water balance.
    If after shocking and making making sure you measure the FC when it's lowest (just before your SWG & pump turn on again, either at night or in the morning depending on whether the pump runs at night), then please let us know as much as possible the actual CYA and FC levels. This helps us adjust our recommendations if we see a pattern. Is the algae regular green algae or yellow/mustard algae?

    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

    Join Date
    Apr 2009
    Location
    Orange Park, FL
    Posts
    104

    Re: Chlorine/CYA Chart

    It's green algae. Am unable to obtain readings after today as I ran out of FAS-DPD reagent. Will order more tomorrow.
    15x30 IG vinyl liner pool, pool cage
    Hayward S-220T high rate sand filter and Hayward super pump w/1hp motor
    Hayward SwimPure Plus SWG
    Polaris 380 cleaner and booster pump

Posting Permissions

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