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Thread: CYA better; need input on TA, CH & CSI

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    CYA better; need input on TA, CH & CSI

    First, thank you for the Pool School. Reading it and the posts, I am developing a basic understanding of some aspects of pool care.

    I purchased a home with a pool (my first) in September 2008. The seller gave me a tutorial on the pool, including a recommendation to keep the 3" tabs in the feeder and add a scoop of dichlor once a week to "shock" it.

    So as you can imagine, when I had the water tested this spring, the CYA was through the roof (maybe 200). After a series of drain/fill cycles, CYA is better. (The puck feeder is now off and the dichlor is no longer in use!)

    Water is crystal clear!

    Here are my current readings (per my local Leslie's since I just ordered a TF-100).

    pH - 7.5
    FC - 3.0
    TC - 3.5
    TA - 60
    CH - 90-100
    CYA - 50
    TDS - 325

    Using the Pool Calculator:
    CSI = -0.81

    If I understand correctly, this is a potential problem for a plaster pool.

    I have several questions:
    1. Do I trust the numbers from Leslie's, or wait until my TF-100 arrives to test myself and correlate with Leslie's?
    2. How urgent is getting the CSI in line? Is the pool wall being damaged?
    3. What's the recommended approach and targets for adjusting my TA and CH to bring CSI in line?
    4. Where is the best location to buy calcium chloride or calcium chloride dihydrate and which is preferred?
    5. Is TDS important? Leslie's measures it, but I haven't noticed it on the TFP posts.

    Thank you in advance for your help!

    Bryan
    20K gal, 34'x 17' ovalish IG plaster; spillover spa 7' dia. round; waterslide & waterfall; built 2004; bought 2008
    Pumps: 2 HP-pool & spa; 1.5 HP-slide & waterfall; C3025 cartridge filter; Navigator w/dedicated line; heater; all Hayward brand

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    frustratedpoolmom's Avatar
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    Re: CYA better; need input on TA, CH & CSI

    Hi Bryan, Welcome

    No TDS is not important. I don't know a whole lot about CSI but I do know that yes, your CH is too low and that's part of the problem. What's interesting is I plugged in your numbers to the calc and got a different result...

    Congrats on figuring out your pool, and successfully lowering the CYA.

    Getting your own test kit was wise, and I would honestly wait until you do your own tests before making adjustments to your other numbers....

    However, if you aim for a target of 200-250 on the calcium though in the meantime, that should be okay. Did they test for "Total Hardness" or Calcium Hardness? As for where to purchase it, you'll have to shop around or call, see who has the best price, either is fine.

    One last thing, you don't have enough FC for your CYA level....check out the chart in my sig. You don't want it to drop below 4, ever, or you risk an algae bloom. Try to keep it around 6.

    Hope this helps!
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: CYA better; need input on TA, CH & CSI

    Welcome to the forum!!

    1. Do I trust the numbers from Leslie's, or wait until my TF-100 arrives to test myself and correlate with Leslie's?
    Wait until your test kit arrives.....there is nothing "urgent" in your numbers and your own testing will be better

    2. How urgent is getting the CSI in line? Is the pool wall being damaged?
    I didn't do the csi, but I think you may have calced it incorrectly. I don't see anything in your numbers that is alarming. Over the next weeks, you should bring your calcium hardness up around 200-300

    3. What's the recommended approach and targets for adjusting my TA and CH to bring CSI in line?
    ABC's of Pool water chemistry in Pool School will give you some guidelines for acceptable ranges and tell you how to get there

    4. Where is the best location to buy calcium chloride or calcium chloride dihydrate and which is preferred?
    I've never purhased it but I think folks that can get it use Dowflake brand ice melter.

    5. Is TDS important? Leslie's measures it, but I haven't noticed it on the TFP posts.
    Disregard it....not important.

    Those are great questions. You are off to a great start in understanding your pool.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: CYA better; need input on TA, CH & CSI

    Thank you frustratedpoolmom and Dave!

    First test results with TF-100:
    FC - 5
    CC - 0.5
    pH - 7.7
    TA - 90
    CH - 150
    CYA - 40

    CSI = -0.16

    Water looks great!

    I will add MA to bring the pH down to 7.5.

    If the CH measurement is correct (used waterbear's technique for the third try), then I need to raise my CH. Pool calculator says to add 296 oz by weight or 237 oz by volume of calcium chloride for a target of 250 (min of recommended range in Pool Calculator using TFP goals).

    I am considering buying one 8lb tub and spreading small amounts at a time across the surface of the deep end (~6.5 ft deep). Then I'll measure after that amount has been added and decide whether more is needed.

    Does that sound about right? How slowly do I need to add it to avoid any heat damage and let it mix? Do I need to measure CH again part way through adding the tub? Have I missed anything?

    Thanks in advance for your help!

    Bryan
    20K gal, 34'x 17' ovalish IG plaster; spillover spa 7' dia. round; waterslide & waterfall; built 2004; bought 2008
    Pumps: 2 HP-pool & spa; 1.5 HP-slide & waterfall; C3025 cartridge filter; Navigator w/dedicated line; heater; all Hayward brand

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    Re: CYA better; need input on TA, CH & CSI

    Hey, Brian,

    very good test results.

    If you calced 296 oz, that's 18 lbs. Are you saying just do 8 lbs to sneak up on it? That'd be great. CH is not an urgent issue so , as long as it's not toally off the carts one way or another, you can adjust it in increments.

    Having never applied it, I can't advise on how best to put it in the pool but someone will be along soon.

    From your posts, you have gained a quick grasp of the concepts taught here on TFP.....nice work!
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    frustratedpoolmom's Avatar
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    Re: CYA better; need input on TA, CH & CSI

    I've applied it. It gets HOT! Especially when you predissolve it in a bucket. Predissolving it is recommended for vinyl liners, but since you have a plaster pool you can just "broadcast" it (sprinkle it) around the pool. Don't be alarmed if your water gets cloudy, that can happen when you make large adjustments to calcium levels.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: CYA better; need input on TA, CH & CSI

    New numbers after adding 8lbs Calcium Chloride:

    FC - 5
    CC - 0
    pH - 7.7
    TA - 90
    CH - 210
    CYA - 40

    I'll bring my pH down to about 7.5 and should be in good shape!

    Is the aeration due to the waterfall and slide going to cause my pH to rise regularly? If so, will adding borates help buffer this?

    Thanks for all the help.

    Bryan
    20K gal, 34'x 17' ovalish IG plaster; spillover spa 7' dia. round; waterslide & waterfall; built 2004; bought 2008
    Pumps: 2 HP-pool & spa; 1.5 HP-slide & waterfall; C3025 cartridge filter; Navigator w/dedicated line; heater; all Hayward brand

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    frustratedpoolmom's Avatar
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    Re: CYA better; need input on TA, CH & CSI

    Yes, borates helps stabilize the PH, if you continue seeing it drift up you can lower the TA to 70. That and the borate addition should help things.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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