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Thread: Rising Alkalinity

  1. Back To Top    #1

    Join Date
    Aug 2008
    Location
    Honolulu
    Posts
    429

    Rising Alkalinity

    This seems odd to me, maybe not to those of you in the know, so any replies would be appreciated.

    I am maintaing both my neighbour who is recovering from major surgery and my pools.

    The balance we had two days ago was as follows:

    FC - 7.5 to 8.0 (mustard gas issues in Hawaii)
    pH - 7.7
    TA - 80
    CH - 350
    CyA - 80
    Salt - 3300
    Borates - 0 (Dogs)
    Temp - 78
    CSI - -0.15 (approximate)

    A few days ago we recieved a moderate amount of rainfall about 2", since then no rainfall to speak of, and unusual for us very little wind, so the pool surface has been glass like versus our normal 16 - 24 mph trade winds.

    All the above numbers have stayed constant, nothing has been added to the pool, the pH today is currently 7.7 with 1oz of acid being added each day per 10,000 gals to maintain pH at around 7.7. Later note added; Just remembered I did up my, but not theirs, CH 25 ppm with Calcium Chloride from 325 to 350 2 days ago, would that have any effect?

    BUT the alkalinity (TA) has risen to 100 in both pools, why would this occur? Normally we are adding Baking Soda to up TA and I cannot remember a time when after it had come into balance that the TA actually rose, although this may have occured in time beyond my memory of it.

    Should I do anything about it, I do not have anyway of aerating my pool but my neighbour has a bubbler in their spa. How long would I need to run the bubbler in their spa, it is a very strong bubbler?

    Should I lower my ph to 7.6, would that help to maintain the CSI at about -0.15 and possibly lower TA?

    Thank you.

    Specs for my pool:

    10,000 gal plaster pool with two long plaster steps (maximum depth 4ft 6 inches) about 18 years old
    3/4 hp WhisperFlo pump (6 hours or about one turn per day - electricty rates are 32 cents to 35 cents per Kilowatt dependant on oil adjustment)
    Sta-Rite Great White GW9500 pool cleaner (constantly moving when pump is on) (with catcher basket and pool sock in both basket and skimmer cleaned every two days)
    PoolPilot Digital SC-60 with pH/acid control (cleaned per manual weekly)
    Hayward 300 lb Sand Filter (sand changed every 6 years and backwashed every 4 to 6 weeks)
    4 oz Algaecide 60 added weekly
    Jack's Magic Purple Stuff maintained weekly and kept at 12 -14 ppm using test kit (to control iron from volcanic dust, aka "Red Dirt, blown in by "Trade Winds")
    10,000 gal plaster pool,3/4 hp WhisperFlo pump, Sta-Rite Great White GW9500 pool cleaner, Hayward 300 lb Sand Filter
    Use Magenta Stuff for Iron and Silica control.
    Balance: pH 7.7 Cl 7 -8 Alk 70-80 CH 325 CyA 30 in winter - 50 in summer NaCl 1010 TDS 1200

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

    Re: Rising Alkalinity

    As long as the PH is remaining reasonably stable, there is no need to adjust TA. It is fairly uncommon for TA to go up like that, though we do hear of it occasionally. One possibility is that some high TA dust got blown into the pool. It is also possible that the difference is the result of testing inconsistency (the TA test is +-10). Since you have PH automation, the acid feed should eventually lower the TA back down.
    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

    Join Date
    Aug 2008
    Location
    Honolulu
    Posts
    429

    Re: Rising Alkalinity

    JasonLion,

    They are doing some home construction further up the mountain so that dust might have come from there.

    Thank you for the reply that is comforting.
    10,000 gal plaster pool,3/4 hp WhisperFlo pump, Sta-Rite Great White GW9500 pool cleaner, Hayward 300 lb Sand Filter
    Use Magenta Stuff for Iron and Silica control.
    Balance: pH 7.7 Cl 7 -8 Alk 70-80 CH 325 CyA 30 in winter - 50 in summer NaCl 1010 TDS 1200

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