Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 3 of 3

Thread: CYA adsorption into pool plaster?

  1. Back To Top    #1

    Join Date
    Feb 2009
    Location
    College Station, Texas USA
    Posts
    32

    CYA adsorption into pool plaster?

    The CYA level in the pool we now own may have been chronically high for some period of time (in excess of 150). This goes back at least a couple of years. A few weeks ago, I made the necessary corrections to get it in the 40 ppm range (basically, drained the pool), and noticed this weekend that it has creeped up to about 70 ppm. I have been using the BBB method for about 1.5 months now (and using ONLY bleach as chlorine source), but recently, because I had no bleach laying around the house, I put a couple of partially dissolved 3" Trichlor pucks in my CL dispenser. My CYA level is now 70. I am a bit surprised that the partially dissolved pucks could have raised the CYA level that much.

    In talking to my local pool store guy, he suggested that the historically high CYA concentration had caused the CYA to adsorb into the pool plaster (because of the super-high levels from prior neglect), and is now diffusing back into the water.

    Does anyone on this board support this possibility?

    I will continue to monitor my CYA level and will use ONLY bleach from now on so that I know for certain that no CYA is added to the water. If I continue to see the CYA rising, then the adsorption/desorption theory would make sense, and eventually, over time, it should stabilize/equilibrate.
    Location: College Station, Texas
    9K gal in-ground plaster pool
    Hayward ProGrid D.E. 2420 Filter
    Hayward Northstar Series 1HP Pump/Motor
    Stenner 3 GPD bleach pump and Pentair 320 Inline Chlorinator

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

    Re: CYA adsorption into pool plaster?

    CYA levels going back up after you do a major water replacement has been known to happen. No one knows for sure what causes it. The stories I have heard are that CYA crystalizes in the pipes and then dissolves when the CYA level in the water goes down. CYA does sometimes go back up, but no one really knows why it happens.
    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
    Guest

    Re: CYA adsorption into pool plaster?

    Quote Originally Posted by psbastian
    In talking to my local pool store guy, he suggested that the historically high CYA concentration had caused the CYA to adsorb into the pool plaster (because of the super-high levels from prior neglect), and is now diffusing back into the water.

    Does anyone on this board support this possibility?

    I will continue to monitor my CYA level and will use ONLY bleach from now on so that I know for certain that no CYA is added to the water. If I continue to see the CYA rising, then the adsorption/desorption theory would make sense, and eventually, over time, it should stabilize/equilibrate.
    Yes, I have seen it time and again. I do not know if the CYA is adsobed into the plaster or deposits in the plumbing and pools surfaces (and I have seen the same thing happen in both fiberglass and vinyl pools also).
    Eventually it will stabilize (no pun intended), but you might have to do the 'drain and refill dance' a few times to get there.

Posting Permissions

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