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Thread: SPA, SWG, CYA question

  1. Back To Top    #1

    Join Date
    Aug 2016
    Montreal, Quebec, Canada

    SPA, SWG, CYA question

    Hello group!

    What a great site this is! I acquired my first spa a few weeks ago and am very impressed at the quality information I found on this site. I am confident I'll be able to better manage my spa with the expertise found here!

    In a nutshell: I have a SPA with a SWG and the pH is unmanageable - always runs high (>8).

    I've read elsewhere that this is a common issue with SPA/SWG. I have also carefully read this post on why high CYA is a good thing with SWG and SPAs in particular.

    My details:
    • 350 gallons (1300 liters); T=95F; 2 bathers every odd day;
    • The spa is covered when not in use; so affected minimally by sunlight;
    • TA: 110 ppm
    • pH: 8.1
    • CH: 110
    • Salt: 800 ppm (ideal 600ppm)
      I know this is low compared to most units currently being sold;
      The manufacturer no longer exists; this is what I found on their old website;
      It does use a Hayward T-Cell-5;
      The only function on the control unit is a timer which turns on/off 6 times a day for a duration I can set;
      I did clean the cell 10 days ago; and I can measure chlorine being produced;
    • TC = 1.5 - 2.0; FC = 1.5 - 2.0;
    • CYA: 0
    • Borates: 0

    I would like to implement CYA & Borates.

    I've been using a dry acid to lower pH but will switch to liquid muriatic acid.

    My plan is to lower TA to 70 or so, which I am in the process of doing right now.

    I use test strips for the time being, and plan to get a Taylor kit in short order.

    • Am I ok in setting TA to 70 as a first step?
    • Then I will lower pH to 7.5 or so, is that Ok?
    • What should I do first: Borates or CYA?
    • I would target CYA of 50ppm or so, and/or Borate of 50 ppm; that okay?
    • Will the calculator on this site suggest proper quantities in my situation?
    • Should I do only one of these two, and monitor for some time (days/weeks) before going ahead with the second?

    Any other suggestions will be greatly appreciated!

    Last edited by presse55; 08-08-2016 at 11:03 AM. Reason: added a few details ...

  2. Back To Top    #2
    Mod Squad
    Join Date
    Aug 2012
    DFW, TX

    Re: SPA, SWG, CYA question

    Welcome to TFP!

    You are on the right track there. Lower TA to 50 though rather than 70. CYA to 30 and borates to 50. Here is a good write up on how to start up a tub with CYA, TA and borates. Yes, PoolMath will work great!

    How do I use Chlorine in my Spa (or pool)?
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