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Thread: CYA and evaporation

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    CYA and evaporation

    Is CYA lost to evaporation or is it just splash-out and rain that would cause it to drop?
    Sue

    18' round Sharkline Matrix AGP / 8600 Gal. / sand filter / Aqua Trol SWG
    Pool owner since 2001. Thanks to TFP for helping me convert off Baquacil after six years!

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    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,085
    Sue,

    Just splash-out, rain overflow, backwashing and other methods of dilution reduce CYA. Evaporation does not reduce any chemicals in the pool as only water evaporates, concentrating the chemicals, and then fresh fill water just brings them back to their original concentration. If there is lots of evaporation, then whatever is in fill water gets added to the pool, so fill water high in TA or CH will increase those parameters.

    CYA can get converted to ammonia by some types of bacteria and this usually occurs over the winter (if it occurs at all) when a pool is "let go" and chlorine is not added. There are some unexplained reports of CYA reduction even when chlorine was present, but most reductions appear to be when chlorine is not present (so that the bacteria can grow). Opening a pool that has had CYA converted to ammonia takes a lot of chlorine to get rid of the ammonia.

    Richard
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

  3. Back To Top    #3
    Thanks. I have to top off about an inch of water every 2-3 weeks when it isn't rainy so I wanted to make sure.

    I think our well water comes from an underground spring, so it's pretty good. I tested it for chlorine and it was zero. One day I should do the other tests on it.
    Sue

    18' round Sharkline Matrix AGP / 8600 Gal. / sand filter / Aqua Trol SWG
    Pool owner since 2001. Thanks to TFP for helping me convert off Baquacil after six years!

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