Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 6 of 6

Thread: Water passing through SWG reaches breakpoint chlorination?

  1. Back To Top    #1
    Olga's Avatar
    Join Date
    Mar 2016
    Location
    Phoenix
    Posts
    21

    Question Water passing through SWG reaches breakpoint chlorination?

    I read an article that mentioned that as water passes through the SWG it reaches breakpoint chlorination and gets rid of chloramines. Then someone commented saying that was a ridiculous statement. Intuitively the notion that breakpoint is reached in the SWG makes sense to me, since at the point of chlorine generation (in the SWG) the chlorine concentration would be incredibly high, thus at breakpoint. I've also noticed that my pool has never needed shock; combined chlorine has not been a problem.

    Google searches have produced no scientific articles that prove or disprove or even discuss this idea. I've found no sales pitches touting it as a benefit either, aside from the one mentioned above.

    Anyone have a link or thoughts?
    17,000 gal. saltwater, Pentair Intellichem, Ozone, Pebble Tech, 50' long negative edge

  2. Back To Top    #2


    TFP Guide

    domct203's Avatar
    Join Date
    Jun 2015
    Location
    CT
    Posts
    3,892

    Re: Water passing through SWG reaches breakpoint chlorination?

    I really can't comment on the chemistry happening inside a SWG cell, but I will add that I have a manually chlorinated (12.5% bleach) pool, and following TFP guidelines my CC's have been pretty much 0.0ppm for three seasons.

    - - - Updated - - -

    Do you have a link to the article you read discussing this?
    Dom - TFP Guide
    Intex 18' X 48" Ultra Frame AGP 6700 gallons | Two Intex CS8110 SWG's | Hayward Pro Series 21" Sandfilter | Hayward 1.5HP Power Flo Matrix pump | Hayward Thru-wall Skimmer | Wanda the Whale | 72 sq ft of Sungrabber Solar Panels with Hayward GLC-2P-A | Taylor K2006 Test Kit, Sample Sizer & Speed Stir | Click Here To Become a TFP Supporter!

  3. Back To Top    #3

    TFP Guide

    Jezza's Avatar
    Join Date
    Jan 2015
    Location
    Bunbury, WA, Australia
    Posts
    948

    Re: Water passing through SWG reaches breakpoint chlorination?

    I would also add that stuff gets into the pool that is oxidized to create CC's long after the SWG has created the chlorine.
    11 000 gallons, IG, Fibreglass, Monarch Sand Filter, Davey Typhoon C100M 1HP pump, Davey Chloromatic Mc16CTO ESR SWG, Davey Pool Wall Climba Robot, Daisy Solar Cover,
    K-2006

  4. Back To Top    #4
    JoyfulNoise's Avatar
    Join Date
    May 2015
    Location
    Tucson, AZ
    Posts
    14,083

    Re: Water passing through SWG reaches breakpoint chlorination?

    First off, let's stay away from the concept of breakpoint chlorination as it is a term used (or should I say, abused) by the industry and it has lots of misunderstanding associated with it. See these posts to understand the fallacies surrounding breakpoint chlorination -

    Certified Pool Operator (CPO) training -- What is not taught

    Is the formula for too high?

    To the idea that an SWG "superchlorinates" the water passing through it, you don't need much science, you just need to look at the numbers. Assume that an SWG is running at the slowest speed possible to generate chlorine which, for most models, is about 15GPM. AT that speed, one would expect the highest level of chlorination possible. For our purposes, let's use an IntelliChlor IC-40 cell -

    1.4lbs/day * (16 oz /lb) / (24 hr/day) = 0.933 oz/hr

    15 gal/min * 60 min/hr = 900 gal/hr

    (0.9333 oz/hr) / (900 gal/hr) = 0.00103 oz/gal of chlorine gas

    In terms of FC, the water inside the cell is seeing roughly 7.8ppm FC. If one has 70ppm CYA in the water (which is the lowest recommended level for an SWG), then the FC/CYA ratio is about 10%. That's hardly "superchlorination". Increasing the flow rate of the water through the cell (most pools operate at 40GPM or more) only dilutes the chlorine further.

    As others have stated, a manually dosed pool that is clean and clear will also have very low CCs. CCs are the by-product of chlorine reacting with bather waste (although not all forms of bather waste produce chemicals that register as CCs) and they usually only high in outdoor pools that are improperly cared for.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

  5. Back To Top    #5
    Mod Squad Jimrahbe's Avatar
    Join Date
    Jul 2014
    Location
    Bedford, TX
    Posts
    9,261

    Re: Water passing through SWG reaches breakpoint chlorination?

    Olga,

    One of the benefits to using the TFP method, whether using a SWCG, or dosing with Liquid Chlorine, is that you never have to add "Shock" to your pool on a weekly basis.

    Thanks for posting,

    Jim R.
    Finished in 2015 - 17K Gal, IG, 20' x 25' Almost Rectangular Pool, Pebble finish, three rockport water falls. Pentair Equipment: EasyTouch 4, IC40 SWG, 3 HP VS Pump, CCP520 Cartridge Filter.
    TF100 with SpeedStir and SampleSizer, ColorQ Pro 7, Dolphin Premier Robot Cleaner, added Screen Logic 2, added small 3 person Caldera Spa.

  6. Back To Top    #6
    Olga's Avatar
    Join Date
    Mar 2016
    Location
    Phoenix
    Posts
    21

    Re: Water passing through SWG reaches breakpoint chlorination?

    Thank you for the comments and explanations. The calculation about expected levels in the cell was very helpful.
    17,000 gal. saltwater, Pentair Intellichem, Ozone, Pebble Tech, 50' long negative edge

Posting Permissions

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