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Thread: CYA Confusion

  1. Back To Top    #1

    Join Date
    Jun 2015
    Villa Rica, GA

    CYA Confusion

    I'm wanting to make sure our CYA is acceptable as long as our chlorine is at a working level/#.....I know our CYA number is high but we've partially drained and added water with hardly any variance in this number....draining the water in a 32K GAL pool is draining my wallet, not to mention the pool has been running nonstop. We went through a 30 day rough patch with cloudiness to algae and now we're clear again. I just want to keep it that way.....
    We had to resort to the use of power powder in our final days of clearing our water. We live in a smallish town and finding plain, normal clorox was becoming a chore with local retailers sold out. Our calcium was low (25) which is why we chose the cal-hypo and are also guessing that use 3" tabs is what caused our high CYA and cloudy trouble to begin with. We're also going to start buying 8.25% bleach in bulk when we make it by our local Sam's
    Current #'s are (from leslie's - our test kit has been ordered!):

    FAC: 5+ (highest they can enter)
    TAC: 5
    CH: 50
    CYA: 100 (also think this is highest they can enter)
    TA: 90
    pH: 7.8
    PHO: 150
    Temp: 77

    Someone recently mentioned keeping the pump off overnight for 12 hours and the CYA will raise to top and then we backwash (from top) and add water.
    If our chlorine stays within a working level and the CYA is high is that ok and is it safe to swim?

    This is our third season of pool ownership and our first issue....I'm wondering if it is because we didn't do a partial drain over the winter??
    20x40 Vinyl IGP / 32,000 GAL / Hayward S200 (currently zeo) Sand Filter

  2. Back To Top    #2
    Mod Squad Texas Splash's Avatar
    Join Date
    Jun 2014
    South-Central Texas, Marion/San Antonio

    Re: CYA Confusion

    Hello bigbaker and welcome to TFP. I think you've already hit the nail on the head. You have a proper test kit on order, so that's priority #1 on its way. But honestly, even with pool store testing (which tends to be inaccurate) we have no idea what your CYA really is. Once it goes over 100, it could actually be much, much higher. All you can do is continue to do partial drains, or in your case with an AG pool, go down to about 1-2 feet at once if you wanted. That's the only way to reduce CYA. You are correct about the previous use of tablets, powders, and other products that have stabilizer in them. Those products are the down-fall of many pool owners.

    Once your get your test kit (TF-100 or Taylor K-2006) you will be able to read FC at much higher levels in hopes of finding a good match between FC and CYA based on the Chlorine/CYA chart (link below). For now, I would suggest you continue to search for good sources of bleach (generic brand is fine), wait for your test kit, and post YOUR numbers once it gets in and we'll be able to determine the best way forward for you at that time. Anything else right now is simply premature.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
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  3. Back To Top    #3
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Tucson, AZ

    Re: CYA Confusion

    Welcome to TFP!!!

    Once the CYA is dissolved in the water, it is uniformly distributed and will not stratify if you leave the pump off.

    That is just one of many inaccurate ideas that seem to float around the pool industry.
    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
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