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

Thread: CYA doesn't make sense

  1. Back To Top    #1

    Join Date
    Jul 2015
    Location
    Rochester, NY
    Posts
    41

    CYA doesn't make sense

    Hi,
    i started my pool about a week and a half ago and added enough CYA to get the levels up to 35. My kit came in last Thursday and I measured a CYA of about 30 (dot disappeared with full tube). We had some rain and I backwashed my filter once, taking maybe 2 inches out of the 45 inch water level. Because I was losing a lot of chlorine in the sun I decided to raise CYA to 40 and last night I put in another 48 oz of liquid CYA. I just measured it now and even with the tube all the way full I could still see the dot. The only possible explanation may be that my water is cooler than 70 degrees I think. I just now read that you ought to raise it to room temperature for testing (by the way, in upstate NY 70 degrees IS room temperature).

    is that it or can there be another explanation?

    other tests:

    FC: 4
    PH: 7.7 (will lower that once people are out of the pool)

    TA was fine a week ago, assuming nothing changed.
    24' round above ground 52" vinyl pool - 12690 gallons at 45'' fill.
    Hayward Power-Flo Matrix SP1510Z1XEHC (1HP, SP).
    Hayward S180T 150lb Sand Filter.

  2. Back To Top    #2
    Mod Squad zea3's Avatar
    Join Date
    Jul 2009
    Location
    Houston, Texas
    Posts
    9,200

    Re: CYA doesn't make sense

    Did you try to perform the test again to make sure you didn't leave any steps out? Are you reading the tests under the same lighting conditions? Also you can pull your sample and let it warm up a bit if the temp is below 70 and try again. One more thing, make sure the pump has been circulating the water at least 30 minutes before pulling a sample.
    TFP Moderator
    Helpful links: TF Test Kits,TFP Pool School, PoolMath
    Vogue 21' round AG, Pentair 1 hp 2 speed pump, 36 sq ft DE filter, Hayward S180T 150# sand filter, Houston, Texas
    Love TFP? Become a
    TFP Supporter!

  3. Back To Top    #3

    Join Date
    Jul 2015
    Location
    Rochester, NY
    Posts
    41

    Re: CYA doesn't make sense

    I re-did the rest this morning:
    i let the pump run for half an hour.
    filled up the bottle at arms-length down the pool.
    Dumped it out to leave water at the 7ml line and filled it up with R-0013 to the 14 ml line
    let it stand in the sun and warmed it up in my hands for about 3-4 minutes.
    It is currently sunny and I held the receptacle at hip-height in the shade while looking down.
    Filled it up all the way and when the surface is still I can still very faintly see the black dot (not as much as yesterday though.

    CYA should be at 45 according to math - it reads less than 30
    24' round above ground 52" vinyl pool - 12690 gallons at 45'' fill.
    Hayward Power-Flo Matrix SP1510Z1XEHC (1HP, SP).
    Hayward S180T 150lb Sand Filter.

  4. Back To Top    #4
    Patrick_B's Avatar
    Join Date
    Jun 2011
    Location
    Midland TX
    Posts
    15,001

    Re: CYA doesn't make sense

    I can't explain it, but if you are confident in the reading, You'll have to add more of you want the increase. I would suggest using powder instead of liquid.
    TFP Moderator
    Essential Links:
    ABC's Of Pool Chemistry, Test Kits, SLAM Your Pool
    28K Gal IG FreeForm, CLI Quartz, Pentair 36"SF & VS Pump, Dolphin M5, Rheem

  5. Back To Top    #5

    TFP Guide

    pabeader's Avatar
    Join Date
    May 2015
    Location
    Dallas Ga
    Posts
    4,064

    Re: CYA doesn't make sense

    I didn't notice you mention the shaking time....
    Bob - Palm Beach by San Juan Pools. approx 5000 gals., Pentair 320 cartridge filter (all new guts installed by me), Goldline SWG, 'New to me' Kreepy Krauly Sand Shark, Intermec 104 Timer Test kit: TF-100 w/Speed Stir

  6. Back To Top    #6

    Join Date
    Mar 2015
    Location
    Harvey, LA
    Posts
    300

    Re: CYA doesn't make sense

    I recommend picking up a bottle of the 50ppm standard solution if you're unsure about your reading...then you can pour till you get to 50 and see what it looks like, or test blindly and see if you get 50 with your methods. I found that I was getting lower numbers than reality because I was measuring at chest height instead of waist height thinking it didn't make a difference...apparently it does.
    17.4k gallon IG pool with attached spa (spa itself is 730gal), Super Blue Diamondbrite plaster, Circupool SI-45+ SWG, BH/Hayward Cartridge Filter, 2hp 2speed Hayward Super II pump, , Jandy Valves, Waterway Skimmers, Rheem 400k Heater, Polaris 360 cleaner, built 2000+-, replastered June 2015, TF-100 kit---Here's my pool test reading history

Posting Permissions

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