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Thread: SWG and water chemistry questions

  1. Back To Top    #1

    Join Date
    Jun 2012
    Location
    West Grove, PA
    Posts
    6

    SWG and water chemistry questions

    Hi Everyone,
    This is my first post here, so I want to thank you all in advance, and also apologize if I forget to mention anything. My signature should have the pool basics and need to know info. I had a pretty bad season last year and then found this site and things have still been work this year, but not nearly as much.

    My biggest issue is around my SWG. I cleaned the cell with muriatic acid at close down last year, and the cell looks good (no scaling) this year - but I am still getting very little reading on my needle on the SWG (it's not at zero, but it's still in the low/yellow area instead of that lovely green area where it sat for our first two seasons with almost no work!) I think I still need more salt, but last season, when I added salt up to about 3900ppm (based on what a pool store told me to do) my solar cover got literally eaten through by the salt. I know I made many other mistakes last year, so I can't just blame that, but I am gun shy on adding more salt, and yet that seems to be what's indicated. I think I need reassurance to pull the trigger.

    We have had very hot weather and with the SWG still not doing it's thing because of low salt level (I assume), I've had to work hard at trying to get everything else where it should be. I had to shock last night because the pool went from sparkly and sitting at about 4FC to cloudy and 0FC with one day of non-attention.

    Here are my most current (this morning) readings:
    FC - 19.5 (post shock last night - right before bed it read 21FC)
    CC - .5
    CYA (weird, it read 30ppm today, but it read 60ppm two days ago, and that seems kind of wrong. I need to buy more reagent today.)
    Ph - 7.6
    TA - 110 (I know this is high - need to add muriatic acid and aerate)
    CH - 170 (I know this is low, hitting pool store today)
    Salt - 3320ppm

    My SWG manufacturer's guide indicates the level for my size pool should be 3500-3700. I know you guys recommend 200 over that level. I added 160lbs yesterday to get it to 3320. My questions are:
    Does the amount of salt register on the salt strip quickly (I added it at 2pm yesterday and took the reading this morning at 9am). Could it actually be significantly higher than the reading I got this morning?

    Does adding salt affect TA, CYA or CH? These numbers for me are a little wonky and I don't want to add anything else that will end up making them worse if I shouldn't.

    At what point should the SWG, assuming I get the salt ppm into the ideal range, kick in to the point that I shouldn't have to continue this mess with my FC? I guess I need to know at what point it's a SWG problem as opposed to a chemistry/balancing problem.

    OK, if anyone sees anything here that is completely crazy or going to blow my pool, up, please let me know. I am a relative novice, but am starting to get a handle on things, I think. Or at least trying to.

    Thanks in advance.
    April
    36.6k gallons, ig, free-form, 8 years old
    Connected spa with small waterfall (currently not hooked up to propane heater)
    2 main pool skimmers
    Large waterfall feature with separate skimmer
    Vanishing edge feature with separate pump/drains

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

    Re: SWG and water chemistry questions

    You should run the pump for 24 hours after adding salt and before testing the salt level again.

    By the by, salt won't ever damage a solar cover. Very high FC levels can damage solar covers, but mostly they just wear out on their own.
    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
    WestSidePool's Avatar
    Join Date
    Jun 2009
    Location
    Cincinnati, OH
    Posts
    424

    Re: SWG and water chemistry questions

    That's a big difference on your CYA.
    CYA shouldn't go from 60 to 30 in two days.
    If it is 30, then there is a good possibility the sun is eating up the chlorine being produced by the SWG.
    I'm not sure where you live, but my pool is in sun almost all day and I have to keep my CYA around 60-70 so the sun doesn't rid my pool of the chlorine it's making.

    And as for the salt level, you want to make the unit happy. If your unit is reading in the range it's supposed to be then there is no need for adding salt.
    Eric

    IG 17x33 Grecian - Vinyl Liner (21k gallons), Hayward Pro-Grid DE 4820 filter, Hayward Super Pump, CompuPool SWG CPSC36, TF-100 Test Kit

  4. Back To Top    #4

    Join Date
    Jun 2011
    Location
    Long Beach, CA
    Posts
    2,670

    Re: SWG and water chemistry questions

    After reading the manual it states that a salt level of 3000-4000 is in a good range with 4000 being prefered. Let the salt circulate for 24 hours and see if you get a higher reading for the salt in the pool from the unit. You might even take it higher than what you are at since this SWG likes a higher salt content. The manual says you will not have problems with the unit until the salt level reaches 5000.

    Make sure your CYA is in the 60-80 range. You didn't say if you adjusted the output % or played with the pump run time. You might need to increase both of these as the cell might be wearing out.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

  5. Back To Top    #5

    Join Date
    Jun 2012
    Location
    West Grove, PA
    Posts
    6

    Re: SWG and water chemistry questions

    Thank you to all...very helpful. My pump has been running for 24 hours a day through this. I added more cya in a sock based on the 30ppm reading, heading to 60 to start (just to give a little space incase the higher reading was actually right).

    I added more salt tonight, about 30lbs, which should get it up to about 3700...I am hoping that moves the needle into the low but ok range. Then I can add more if I want to be up near 4000.

    My fc was still 19.5 tonight and cc was still.5. So somehow all day in the sun, fc didn't run down? This confused me a bit. Perhaps the swg is doing something now and producing chlorine that is adding to the effects of the shock treatment I did last night? I did not add more bleach tonight. The water is still cloudy, but not at all green, and the cloudy seemed less cloud adjust a touch more clear than yesterday. I brushed sides and floor. I pulled the cover off and rinsed the heck out of both sides, hoping to get any residual chlorine off from the high fc numbers. Hoping not to have a shredded cover again. Thanks, Jason, for letting me know that salt doesn't do that but high fc can. It was a brand new cover last season! And now I have another brand new cover.

    So I'll check levels again in the morning and update. Thanks, all.
    36.6k gallons, ig, free-form, 8 years old
    Connected spa with small waterfall (currently not hooked up to propane heater)
    2 main pool skimmers
    Large waterfall feature with separate skimmer
    Vanishing edge feature with separate pump/drains

  6. Back To Top    #6
    WestSidePool's Avatar
    Join Date
    Jun 2009
    Location
    Cincinnati, OH
    Posts
    424

    Re: SWG and water chemistry questions

    Just remember it can take CYA up to a week to register on the test, so you want to add it a bit at a time, so you don't overshoot your number.
    Eric

    IG 17x33 Grecian - Vinyl Liner (21k gallons), Hayward Pro-Grid DE 4820 filter, Hayward Super Pump, CompuPool SWG CPSC36, TF-100 Test Kit

  7. Back To Top    #7

    Join Date
    Jun 2012
    Location
    West Grove, PA
    Posts
    6

    Re: SWG and water chemistry questions

    FC was holding very high this morning...17.5.
    CC was still .5. Oh had dropped a touch to 7.4.

    It's looking much better. Thanks for your help folks. Hoping the segment gets going and the cya helps
    to hold the FC level.
    36.6k gallons, ig, free-form, 8 years old
    Connected spa with small waterfall (currently not hooked up to propane heater)
    2 main pool skimmers
    Large waterfall feature with separate skimmer
    Vanishing edge feature with separate pump/drains

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