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Thread: Low TA/High FC Question

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    Low TA/High FC Question

    New to the forum, first time posting, I appreciate the help on this. I bought the TF-100 Pool testing kit about 3 months ago and have been testing my pool with it (its great by the way!).

    Current Readings this morning are:

    FC: 13.00
    CC: 00.50
    TC: 13.50
    CY: 38.00
    CH: 220.00
    PH: 7.50
    TA: 45.00

    Two questions. First, my TA has slowly been going down over the last 3 months, from a reading of 85 beginning of August, to 45 today (been a gradual decline). What is causing this, and what, if anything should I do to increase the TA in my pool? The PH levels in my pool always trend on the high side (7.8 range if I am not staying on top of adding muriatic acid regulary, about a 1-2 cups per week).

    Second question, my FC levels have been consistently running high as well (in the 10-14 range) over the last 3 months. I have tried adjusting the % down on my SWG, as well as the number of hours my pool pump is running, yet it still remains on the higher end. Is this something I should be concerned about? I have a Pentair IntelliChlor, and right now its set to 25% in Pool Mode, and the pump is running about 7 hours a day at 2200 RPM (in Houston, Texas). Salt PPM is reading 2,800 (on my remote).

    To clarify, I am not having any visible issues with the pool, or comfort issues, its just all about the numbers that have me asking these questions. I have an inground pool, about a year old, pebbletec finish, about 14,000 gallons, SWG. I appreciate any feedback you can provide.

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    Mod Squad jblizzle's Avatar
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    Re: Low TA/High FC Question

    Welcome to TFP!!!

    Your FC is certainly higher than it needs to be. So you have to either turn the SWG % setting down more or shorten the pump run time.
    Really in the summer you should raise your CYA up closer to the 70-80ppm recommendation for SWG pools.

    There is nothing wrong with the pH being up around 7.8. The SWG will tend to drive the pH up and when you add acid, that will lower both the pH and the TA. You TA is bordering on being too low, but with the lower TA, the pH should not rise as fast. I might try to see if the pH stabilizes around 7.8 and only lower it if it gets above 8.0.

    You also may consider raising the CH into the recommended range so that your pebble finish is not damaged ... i would certainly not make the pH lower than 7.5 with the low CH values.
    Jason, TFP Moderator
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    Re: Low TA/High FC Question

    Thanks for the tips. I have been adjusting my SWG down for the last 3 months and still the higher FC levels. I'll keep inching it down till I stabilize in the single digits and see how that goes. When I first got the pool, I was having a hard time keeping FC in the 4-5 range, and was running it much more, but realized I didn't have adequate CYA at the time. I'll raise it up next Spring (unless it gets too low over the winter).

    Thanks for the note on Ph. The tap water in our neighborhood is actually 7.8 on average, so I see your point, I had just always read 7.2-7.8 so was trying to keep it in the middle.

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    Re: Low TA/High FC Question

    Ok, so I made a few adjustments this week (adding some stablizer/baking soda, etc... to get my TA up, CYA up, and CH up). I also put a bag of salt in to get my ppm up within range for my chlorinator, and then I adjusted my SWG down 25% to 20%, and from 7 hours pump time to 6 hours pump time per day to see if I could get my FC # down. Here are the results.

    FC: 19! (up from 13 last week, even though I lowered my SWG output and hours)
    CC: 0 (down from 0.5 last week)
    CYA: 55 (up from 38 last week, should I get it higher, or wait till Spring?)
    CH: 285 (up from 220 last week, pebbletec pool, should I get it over 300?)
    TA: 80 (up from 45 last week, feels like that is a good number)
    PH: 8.2 (up from 7.5 last week, I didn't put any acid in until I got the CH number up, assume this went up with the TA going up, will add a cup of acid to try and get it back in the 7.8 range)
    Salt: 3050 PPM (up from 2,800 PPM last week)

    Pool still looks great, just wondering why I am having such a hard time keeping the FC level down? I use to run the pool 8-9 hours a day, at 40% output, and would be in the range of 5-6. Not swimming in it right now, but want to figure it out.

    Thanks for your help/guidance.

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    Mod Squad jblizzle's Avatar
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    Re: Low TA/High FC Question

    Turn down the SWG or shorten the pump run time some more.
    I would wait until spring to raise the CYA more
    CH should be fine
    I would not raise the TA any more than that
    lower the pH a bit like you stated

    When the water cools and sun is less intense the FC consumption goes WAY down. I am struggling to get my FC down and SWG dialed in as well.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: Low TA/High FC Question

    Turn the SWG to 0% until the FC drops to the high end of your target and then turn it back on at 15% and check it daily to make sure it is dialed in.

    It's that time of year when pools stop using so much chlorine and SWG's need to be dialed down along with pump run time.
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    Re: Low TA/High FC Question

    Thank you both!

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