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Thread: How much Aeration needed for Ph Rise

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    How much Aeration needed for Ph Rise

    So i just filled up my new hot tub, after running Ahh-some through it. Very surprised at how much gunk was coming out considering the hot tub was manufactured within the last 5 weeks.

    THen drained, rinsed and refilled.

    Added roughly 3 ppm chlorine(did not test to confirm this level was reached), 100 ppm CH, roughly 30 ppm CYA (still will need to wait to confirm this level ends up correctly). Added Spa Marvel. Ran jets for the 20 min cycle. let hot tub sit with just the circ pump and water fall on for a few hours.

    Tested water

    FC 1 ppm (chlorine was purchased in April, so could be a bit weaker)
    PH 7.5
    CH 100ppm
    Borates 0
    Alk >200 ??? Not sure why so high
    CYA not tested yet, will wait a few days for it to disolve


    So added about 100ml of Muriatic acid last night and put the jets on 20 min cycle. This amount should lower my pH to 7.0 based on on water volume

    My question is.

    Will 20 min cycle be enough to raise pH back up, or will i need more time? It was late, so after 20 min i closed lid and went to bed. Will check tonight, but just curious.

    I'm wondering why my TA is so high, maybe reagent is bad? it is so high, i stopped at 20 drops. I will need a lot of Acid cycles to lower and then raise pH. Maybe tonight i can do a few cycles?


    Rgds
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

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    Mod Squad JVTrain's Avatar
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    Re: How much Aeration needed for Ph Rise

    Test your fill water for pH, CH and TA. The water out of my tap (city water) routinely has CH of about 350 and TA of 280 ppm or higher. Your high TA is likely from the fill water. You'll have faster pH rise until you get the TA down to less than 100 ppm. My pump runs whenever it needs to increase the temp and during it's daily 2 hour filtration cycle. If you want it to aerate to intentionally raise pH, then set your filter/pump cycle to run continuously. Failing that... leave the cover off and set it for 105 degrees. But that will waste $ on the heater running as well.

    UPDATE:

    Initially when I fill my spa with 200+ TA fill water, within and hour of aeration, my pH is over 8.2. Goes like that until I get below 200, then it takes a little longer after each time I add acid until it's fairly stable at 60 ppm TA.
    Last edited by JVTrain; 08-31-2016 at 09:07 AM. Reason: My experience with high TA.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

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    JoyfulNoise's Avatar
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    Re: How much Aeration needed for Ph Rise

    Why did you use Spa Marvel if you already used Ahh-some? It's a bit redundant and there's no telling what the spa marvel added as all the chemicals in it are listed as proprietary. It's listed with an alkaline pH of ~9 so it may have added to your alkalinity.

    What's your fill water TA?

    Hard to tell how much aeration will raise pH but you should leave the tub uncovered to promote outgassing of CO2.

    Did you raise CYA independent of FC or are you following the dichlor then bleach method?
    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

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    Re: How much Aeration needed for Ph Rise

    I have well water and i run through softener, otherwise my CH would be > 300ppm. I've never had that high TA in my pool? I have a continuous circ motor so small waterfall is running continuously. Will check tonight both tap water and try and get TA down.
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

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    Re: How much Aeration needed for Ph Rise

    Quote Originally Posted by outdoor View Post
    I have well water and i run through softener, otherwise my CH would be > 300ppm. I've never had that high TA in my pool? I have a continuous circ motor so small waterfall is running continuously. Will check tonight both tap water and try and get TA down.
    OK, I think i have my chemicals fairly balanced with exception of pH which is high

    FC ~3
    AK 80
    CH 120
    CYA 60
    Borates 50
    pH seems high showing as 8.2

    I did have pH down to around 7.5, but it raised again. Should i lower my Alkalinity more?
    Should i not leave the fountain on? My circ pump is on 24/7 as the dealer suggested. It is separate circ pump, small amperage that apparently you leave on all the time

    the fountain flows right into the filters, so i figured it was helping filter more water. Could that little amount raise pH that much?

    how do i get pH down without impacting TA if it is already at a good level?
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

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    Re: How much Aeration needed for Ph Rise

    Quote Originally Posted by outdoor View Post
    OK, I think i have my chemicals fairly balanced with exception of pH which is high

    FC ~3
    AK 80
    CH 120
    CYA 60
    Borates 50
    pH seems high showing as 8.2

    I did have pH down to around 7.5, but it raised again. Should i lower my Alkalinity more?
    Should i not leave the fountain on? My circ pump is on 24/7 as the dealer suggested. It is separate circ pump, small amperage that apparently you leave on all the time

    the fountain flows right into the filters, so i figured it was helping filter more water. Could that little amount raise pH that much?

    how do i get pH down without impacting TA if it is already at a good level?

    Anyone?
    Located in Ottawa, Ontario Canada
    23K Gal, AG, Cart filter, 1.5hp 2speed hay PowerFlo Matrix, Install Sum'13, Aquatrol SWG, Solarbear panels, kreepy Krauly E-Z Vac, TF-100
    Artesian ~500gal Grand Gayman Island Spa

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    Mod Squad JVTrain's Avatar
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    Re: How much Aeration needed for Ph Rise

    It's fine to lower your TA to 60 or even 50 ppm in a spa. Spas have lots of aeration so pH rise will happen faster and lower TA is acceptable. If it goes below 50 ppm, you may have issues with pH bouncing around more erratically with chemical changes. When your TA gets lower, try only lowering your pH to 7.4 or 7.6. pH tends to be more stable in at 7.6 and 7.8 than it is at 7.2.

    Your CYA is relatively high in the spa at 60 ppm. You only really need 20-30 ppm CYA in a spa since there is not much sunlight exposure, provided the spa is covered when not in use. CYA in a spa is simply to buffer the strength of the chlorine and allow easier maintenance of FC levels. I wouldn't worry about draining to lower it, just make sure you always have some FC in the spa and feel free to raise the FC as high as ~16 ppm after soaks with the higher CYA, to deal with residual organics (bather waste).
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

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