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Thread: Gazebo over spa (no sun) = no need for CYA?

  1. Back To Top    #1

    Join Date
    Jun 2016
    Location
    Grand Haven
    Posts
    6

    Gazebo over spa (no sun) = no need for CYA?

    Hi all,

    This is my second post, I'm new to TFP. I have a TF100 that I use for my pool, but I haven't yet tested my spa water because I was using dichlor and the CYA is very high. I'll do a drain and refill soon. (While I've used the TF100 CYA test for my pool, I'm basing my high CYA level in the spa on results obtained with Aquacheck test strips, which show the CYA off the high end. I don't want to 'waste' a TF100 CYA test on water I plan on replacing soon...)

    Here's my question: When I drain and refill, will I need to add CYA, by whatever method, even though my spa is under a gazebo and never sees the sun, except, perhaps for an hour or so very late in the day, if the cover is off (rare)? If CYA is primarily for UV stabilization, I'd think I could skip it if the spa doesn't see direct sun.

    Any thoughts?
    Kerry
    Pool: ~21,000 gallons, in ground, vinyl, sand filter
    Spa: 450 gallons, above ground under gazebo, fiberglass

  2. Back To Top    #2
    Richard320's Avatar
    Join Date
    Jan 2010
    Location
    San Dimas, CA (LA County)
    Posts
    18,768

    Re: Gazebo over spa (no sun) = no need for CYA?

    Quote Originally Posted by KerryR View Post
    Hi all,

    This is my second post, I'm new to TFP. I have a TF100 that I use for my pool, but I haven't yet tested my spa water because I was using dichlor and the CYA is very high. I'll do a drain and refill soon. (While I've used the TF100 CYA test for my pool, I'm basing my high CYA level in the spa on results obtained with Aquacheck test strips, which show the CYA off the high end. I don't want to 'waste' a TF100 CYA test on water I plan on replacing soon...)

    Here's my question: When I drain and refill, will I need to add CYA, by whatever method, even though my spa is under a gazebo and never sees the sun, except, perhaps for an hour or so very late in the day, if the cover is off (rare)? If CYA is primarily for UV stabilization, I'd think I could skip it if the spa doesn't see direct sun.

    Any thoughts?
    CYA also acts as a buffer. Think of buffered aspirin. It sort of takes the harsh edge off without lessening the effects.

    3 FC at 30 CYA is actually easier on hair and skin and swimsuits than 1 FC at zero CYA. At 1 FC and zero CYA, you'll have .5 Cl2.
    3 FC at 30 CYA will be .06 Cl2



    The graph and a lot more technical info is in this thread: Pool Water Chemistry
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

  3. Back To Top    #3

    Join Date
    Jun 2016
    Location
    Grand Haven
    Posts
    6

    Re: Gazebo over spa (no sun) = no need for CYA?

    Thanks for the info!

    I'll get some CYA into the water after I refill.

    Interesting graph-- it also appears to illustrate why we need higher chlorine concentrations in the solution as CYA goes up, and that bacteria and algae don't die off at the same saturation. Cool stuff.

    Thanks!
    Kerry
    Pool: ~21,000 gallons, in ground, vinyl, sand filter
    Spa: 450 gallons, above ground under gazebo, fiberglass

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