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Thread: PH - Alkalinity Question

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    PH - Alkalinity Question

    So... 3 full weeks into my first pool and everything seems to be going great thanks to all the help from you folks. Just learning some final tweaks for peace of mind really. Any help would be appreciated.

    After week one I had these results from testing
    FC goes down to about 4 and I bring it up to 7.5 or 8 every day. LOTS of sun on my pool.
    CC 0
    PH 7.8 +maybe
    Alkilinity 120
    CH 140
    CYA ~ 50 or 60

    So I added Muriatic Acid to bring down the PH. Tested again the same day. Changes were:
    PH went from 7.8+ to 7.3
    Alk went from 120 to 90 or 100

    I left well enough alone.
    After week 2...
    FC good
    CC 0
    PH 7.5
    ALK 100
    CH 140
    CYA ~55

    Things looked pretty good. I noted a slight rise in PH.

    After week 3 (yesterday)...
    FC Good. Seems to steadily lose up to 4ppm daily depending on sun. I noticed on very cloudy days I lose less. As little as 2ppm a couple times.
    CC 0
    PH 7.7 another rise
    ALK 100
    CH 140
    CYA ~55

    So now Im wondering... PH is rising without a rise in Alk. .2 per week I am noting. Time for more acid I think. But from what I read my Alk should be between 90 and 120. If I use more acid, it seems I will drop below that 90 mark. (is that ok?) And if this keeps on?

    On the pool return I have, there is nothing on the inside of the pool. Meaning that the return shoots straight into the pool 6" or so below the water line. There is nothing there for me to turn and make the water shoot lower. So... is it possible that the return ripples are aerating the water? Causing PH to rise? Is doesn't splash or bubble really but I do see rippling out for several feet from the return.

    I'm looking to solve this before I add more acid because from what I read in pool school this seems like "aeration" causing this. But Im also 3 weeks into pool ownership. Any thoughts?
    24' AG (still learning details)
    1.5hp pump
    Clear Water High Rate Sand Filter 22"

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    Mod Squad pooldv's Avatar
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    Re: PH - Alkalinity Question

    Yes, it is fine for TA to drop lower if that is where it ends up, down to 60 would be OK. Adding a little acid every few weeks to lower PH slightly is normal. Over time that will lower your TA and your PH and TA could reach equilibrium and remain stable. Or you might have to add a little acid every few weeks. Because your TA is in range just maintain PH between 7.5 and 7.8. Let TA end up wherever it wants to be.
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    Re: PH - Alkalinity Question

    Quote Originally Posted by Mojin7 View Post
    So... 3 full weeks into my first pool and everything seems to be going great thanks to all the help from you folks. Just learning some final tweaks for peace of mind really. Any help would be appreciated.

    After week one I had these results from testing
    FC goes down to about 4 and I bring it up to 7.5 or 8 every day. LOTS of sun on my pool.
    CC 0
    PH 7.8 +maybe
    Alkilinity 120
    CH 140
    CYA ~ 50 or 60
    Don't let your FC drop to 4ppm, especially if you are above CYA of 50ppm. If you are getting "between 50-60" on the CYA test it would be best to go with a CYA of 60ppm & maintain a target of no less than 7ppm.

    Letting your FC drop to the minimum of your CYA range is asking for algae trouble.

    Dom
    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!

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    Re: PH - Alkalinity Question

    Quote Originally Posted by pooldv View Post
    Yes, it is fine for TA to drop lower if that is where it ends up, down to 60 would be OK. Adding a little acid every few weeks to lower PH slightly is normal. Over time that will lower your TA and your PH and TA could reach equilibrium and remain stable. Or you might have to add a little acid every few weeks. Because your TA is in range just maintain PH between 7.5 and 7.8. Let TA end up wherever it wants to be.
    Ok Thanks. So if this keeps going at this rate though, you think if my TA gets down to 60 I should start getting concerned maybe? Otherwise you are saying to just see if it stabilizes itself? Just concerned that Ill be dropping out of the "main stream" range I keep reading of 80 to 120 or 90 to 120. Thanks for the info.

    - - - Updated - - -

    Quote Originally Posted by domct203 View Post
    Don't let your FC drop to 4ppm, especially if you are above CYA of 50ppm. If you are getting "between 50-60" on the CYA test it would be best to go with a CYA of 60ppm & maintain a target of no less than 7ppm.

    Letting your FC drop to the minimum of your CYA range is asking for algae trouble.

    Dom
    \

    Do you think it would be better to bring it up to 8.5 daily so my low is closer to 4.5? I guess I haven't been super concerned because my pool gets almost nothing in it.
    24' AG (still learning details)
    1.5hp pump
    Clear Water High Rate Sand Filter 22"

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    domct203's Avatar
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    Re: PH - Alkalinity Question

    Every night after dinner I bump the pool to 10ppm.

    Next day when I get home from work the FC is 6.5-7.5ppm.

    Lowest I've seen it so far is 5.5ppm

    Dom
    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!

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    Re: PH - Alkalinity Question

    Same here...with a CYA of 60, I get nervous when FC gets to 5ish and I even have a SWG. At least once a week after a lot of sun or bather load, I'm still supplementing with liquid bleach to be safe. I don't want to go through another SLAM
    18' x 38' Pool, 3' to 8' Depth
    Vinyl Liner
    SWG
    Variable Speed Pump
    Sand Filter

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