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Thread: potassium peroxymonosulfate shows as CC

  1. #1
    Junior Member
    Join Date
    Jul 2011
    Posts
    27

    potassium peroxymonosulfate shows as CC

    I have a question about the non chlorine shock (potassium peroxymonosulfate).
    How long does it give false CC readings? I cant shut down my pool for 1-3 days using the super-chlorination method (kids will kill me). Other than the expense is there any issues using the potassium peroxymonosulfate over super-chlorination?
    15.5k pool, BBB method used, Plaster in ground pool, DE filter, full sun in Boerne, tx, NO SWG.

  2. #2
    Senior Member
    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    9,449

    Re: potassium peroxymonosulfate shows as CC

    MPS shows as CC in a DPD chlorine test, but it shows up as FC in a FAS-DPD chlorine test. The reason is that it does not react with the dye itself, but does react with potassium iodide (the CC measuring reagent) in the DPD chlorine test and it reacts with the FAS-DPD titrating reagent during the FC part of that test. Taylor makes an interference remover, the Taylor K-2042 that will let you measure the chlorine vs. MPS readings separately.

    As for how long it takes for the MPS levels to drop, that depends on how much there is to react in the pool. Usually it's a day or two. Note that some people still use their pools right after initial shocking, just when the chlorine levels start to drop from shock level. The active chlorine level is still a lower during shocking (around the equivalent of 0.6 ppm FC with no CYA) compared to most indoor commercial/public pools (around 1-2 ppm FC with no CYA).

    Also note that when a pool is properly maintained, you don't need to shock it regularly.
    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"

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