Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 6 of 6

Thread: Confused about CYA need

  1. Back To Top    #1

    Join Date
    Apr 2011
    Location
    Brookeland, Texas
    Posts
    89

    Confused about CYA need

    I know I read the purpose for CYA a 100 times or more here. But I am still confused about it. I have a couple of questions I need explained to help me better understand the need for it.

    What does it actually do for my Chlorine level?

    I understand that it protects from chlorine loss due to UV sunlight, but why then is it the higher my cya is the higher my FC levels have to be?

    In otherwords it seems to me that cya protects a certain amount of chlorine from sunlight consumption, but then I need more chlorine because the chlorine bound to the cya is usless??????

    I know I'm missing something here, please shed some light on this for us more simple minded people.
    12k gal. Free form 14' x 28' IG gunite, 8' raised spa, Hayward T15 SWG, Hayward Ecostar VS pump, Hayward Super II pump, Booster pump, Polaris 280, Hayward DE 7220 filter, 400k Btu heater, Color logic LED lights. Pro Logic controller with remote.

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: Confused about CYA need

    You almost have it. Essentially, CYA does two main things. It protects FC from being lost to sunlight, and it "buffers" the chlorine, holding some percentage in reserve (ineffective but available in case the FC level goes down). Both effects increase as the CYA level increases. To compensate for the chlorine held in reserve, you need to raise the FC level as the CYA level goes up to keep the same active chlorine level. Despite this, you still lose less chlorine to sunlight as CYA goes up.
    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
    Apr 2011
    Location
    Brookeland, Texas
    Posts
    89

    Re: Confused about CYA need

    So does this mean that if and or when the useable FC drops then the cya bound or buffered chlorine is then released as back up?
    Thanks Jason,
    I guess the reason this doesn't make sense to me is in the case of a SWG pool. The CYA recommended levels are higher then a manual dosed pool. If SWG is producing chlorine at basically a constant level, as long as the pump is running, then why would I need higher CYA to hold chlorine in reserve when it is constantly dosing the pool with new chlorine? And if this is true the higher the CYA the harder my SWG has to work to keep levels high enough to compensate for the cya levels? It makes sense for a manual dosed pool where chlorine is only replaced when put in??
    12k gal. Free form 14' x 28' IG gunite, 8' raised spa, Hayward T15 SWG, Hayward Ecostar VS pump, Hayward Super II pump, Booster pump, Polaris 280, Hayward DE 7220 filter, 400k Btu heater, Color logic LED lights. Pro Logic controller with remote.

  4. Back To Top    #4
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Location
    Tucson, AZ
    Posts
    37,389

    Re: Confused about CYA need

    You missed the point that at a higher CYA there is LESS FC consumption everyday. So the SWG actually does not have to work as hard to maintain a level. It would have to work harder to raise FC from zero, which is why we say to add bleach to initially raise the FC up and then allow the SWG to maintain it.

    Posted with Tapatalk ... sorry if I sound short ... hate typing on phone
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  5. Back To Top    #5
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: Confused about CYA need

    Quote Originally Posted by tcm
    So does this mean that if and or when the useable FC drops then the cya bound or buffered chlorine is then released as back up?
    Yes, exactly. As the active chlorine gets used up, the CYA releases some of the bound chlorine to become active again. The amount bound up by CYA is always some percentage of the total FC level, with the specific percentage depending on the CYA level.

    This has a couple of advantages. For example, without any CYA, high FC levels can damage hair. But with CYA you can have much higher total FC in the pool available for sanitizing, but the active level is lower so no hair damage.

    The ideal CYA level is a balancing act. Higher CYA means less chlorine lost to sunlight. But higher CYA also means problems fighting algae (because shock level goes up and the total amount of chlorine involved becomes expensive and annoying). With a SWG the balance shifts to higher levels because higher CYA levels mean less total chlorine used so longer cell life, and SWG pools are less likely to get algae so not as important what happens when you do get algae.
    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

  6. Back To Top    #6

    Join Date
    Apr 2011
    Location
    Brookeland, Texas
    Posts
    89

    Re: Confused about CYA need

    Thanks Jason,

    The water in my head is a little less cloudy now. Need to shock the brain every now and then.
    12k gal. Free form 14' x 28' IG gunite, 8' raised spa, Hayward T15 SWG, Hayward Ecostar VS pump, Hayward Super II pump, Booster pump, Polaris 280, Hayward DE 7220 filter, 400k Btu heater, Color logic LED lights. Pro Logic controller with remote.

Posting Permissions

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