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Thread: Secondary determinants in FC lost to sunlight

  1. Back To Top    #1

    Join Date
    Jul 2009
    Norman, OK

    Secondary determinants in FC lost to sunlight

    I'm curious what factors impact the amount of free chlorine that's lost to sunlight. Obviously, CYA levels and available sunlight (UVA/UVB radiation?) are primary determinants. However, given any fixed amount of CYA and sunlight, will your free chlorine lost to sunlight be a function of total free chlorine available? Or is it a function of the surface area of the pool? Or volume of the pool? Or all of the above?

    For my CYA level (50), my target FC is from 4-8. I'm wondering whether I'll lose more FC each day if I run my pool at the top of the spectrum as opposed to the bottom.
    My details: 16x32+swimout, 14,300 gallon, gunite/plaster pool, Jandy CL460 cart filter, 1.5 hp Stealth Pump, QuikClean six zone in-floor cleaning system, QuikPure QP3-25 Ozonator

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

    Re: Secondary determinants in FC lost to sunlight

    FC lost is a percentage of the starting FC level, so the higher your starting FC level the more FC you lose to sunlight.

    You need to keep FC at the minimum level regarless, so you often have to raise the FC level towards the top of the range each evening just to make sure it is still at the minimum the next evening (unless you add chlorine more than once a day).
    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

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