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Thread: pH of 7.4 or 7.3 ?

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    pH of 7.4 or 7.3 ?

    Would it be harmful in getting my pool to a pH of 7.3 or 7.4 range when I treat it with acid. When pH gets to 7.8 I drop it to pH 7.5

    For kicks I sometimes check it & sometimes it’s a tad below 7.5, man it sure needs less chlorine the lower the pH is. It has gotten to the point where I don’t even bother checking pH until the chlorine demand goes up more than usual- then I know my pH is creeping up to where I need to be checking it.

    FWIW, I had a calcium scaling issue (winter pH got too high for too long) that I tried to correct with various acid treatments that were unsuccessful, I haven’t re-plastered & won’t until I have to.

    Current tests & been stable all summer- pool has behaved spledidly all summer
    Borates 25
    TA 50 & has been all summer & doing great
    CC 0
    CYA 45
    CH 300

    Thank you
    19,800 gallons (closed/winter 18,654 gal); plaster; 18x34 Ft kidney bean shape, Depth 3Ft-5Ft. Built 1992
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    JasonLion's Avatar
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    Re: pH of 7.4 or 7.3 ?

    Taking the PH down as low as 7.2 for fairly short periods is always totally fine. You don't always want to do that on purpose, for example lower PH tends to cause more PH drift, but if it happens now and then it isn't a problem.

    TA around 50 is fairly low, particularly without any borates in the water. I don't recommend TA below 60 without borates. 50 is not really a problem, but you don't want it going below that, so keep an eye on it.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Richard320's Avatar
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    Re: pH of 7.4 or 7.3 ?

    No.
    I try to keep mine around 7.4, since I read somewhere that that's the pH of human tears.

    Plus I have a lot of CH, so I need to watch the CSI.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    frogabog's Avatar
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    Re: pH of 7.4 or 7.3 ?

    Richard,

    How does it feel? I ask because 1) I don't bother to swim so I ask my kids, and 2) when I had the pH at 7.4 the kids said their eyes stung a little. I've brought it up to 7.5, maybe 7.6 and the kids say it's better.

    I also have cold water. So, I think that might be a factor as well. Trying to find the right pH for eyes has been difficult for me this season. It's not 7.4 for sure. Pool was holding at 7.7 earlier this season and the eye issue was hit and miss (kid report). Then I stuck two 3" pucks in it, pH went down to 7.2 and I had to aerate. Takes me two full days to aerate a tenth up with my hokey aeration techniques.

    I've been wanting to ask how everyone's eyes feel at different pH levels. The kids seem very sensitive to the normal range, needing something specific that I am not sure I have figured out quite yet. Thoughts?

    (prolly should be a new topic, but it seems to fall into this one as well. How does the OP's eyes feel?)
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
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    Re: pH of 7.4 or 7.3 ?

    See this post. According to the studies, a range of pH from 7 to 9 is not irritating to the eyes, but the eyes are much more sensitive to the salt level where higher is better (well, ocean salt levels are too much, but normal pool levels are all below the 9000 ppm level in tears). Now chloramines, especially nitrogen trichloride, is very irritating and more of it is produced at lower pH, but with CYA in the water their level should be negligible. So I'm not sure what accounts for your kids reporting that 7.4 is irritating while higher pH is not. I've had the pH from 7.0 to 8.0 at various times in the pool (the former during TA lowering) and I never noticed any difference for my eyes.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    frogabog's Avatar
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    Re: pH of 7.4 or 7.3 ?

    I hardly ever see CC. I test frequently.

    They report honestly. They know I need accurate reports. The community center pool down the street always leaves them with bad eyes. They tell me when our pool is off. They know it can be perfect.

    " mom, the ph is off..."

    Tfpkids for certain, lol.
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

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    Richard320's Avatar
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    Re: pH of 7.4 or 7.3 ?

    Quote Originally Posted by frogabog
    Richard,

    How does it feel? I ask because 1) I don't bother to swim so I ask my kids, and 2) when I had the pH at 7.4 the kids said their eyes stung a little. I've brought it up to 7.5, maybe 7.6 and the kids say it's better.
    It feels like nothing. When I get out of the pool, I may as well have just gotten out of the shower. No smell, no red eyes, no itchy skin, no dry hair.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: pH of 7.4 or 7.3 ?

    If 7.0 pH is classified as neutral, wouldn't 7.0 to 7.2 pH be best for a marcite pool? In other words, in that range the water in neither acidic (that would cause pitting) nor alkaline (which would encourage scaling).
    21K - marcite - inground - Autopilot 48 SWG - 240 sq ft Pentair filter - 2hp 2sp Pentair pump - solar heater

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    Re: pH of 7.4 or 7.3 ?

    Quote Originally Posted by splash
    If 7.0 pH is classified as neutral, wouldn't 7.0 to 7.2 pH be best for a marcite pool? In other words, in that range the water in neither acidic (that would cause pitting) nor alkaline (which would encourage scaling).
    Whether or not the plaster will scale or dissolve depends on the calcite saturation index (CSI), which depends on multiple factors. You can use the pool calculator to calculate the index.

    http://www.thepoolcalculator.com/

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    Re: pH of 7.4 or 7.3 ?

    Quote Originally Posted by frogabog
    How does the OP's eyes feel?)
    I'm not a big swimmer, so no help. Nobody complains. It is not at 7.3 or 7.4 for too long because it always creeps up.

    Right on re keeping an eye on it Jason, you helped me last season when I 1st discovered a TA of 50 is good for my pool. My Borates are 25 as I say. I always figured I'd not replenish my borates when they are gone,but, based on well my pool has behaved this season, I may re-think that if I have issues w/out borates.

    My TA of 50 has been 50 since opening & I have not needed to add anything to keep it there.
    19,800 gallons (closed/winter 18,654 gal); plaster; 18x34 Ft kidney bean shape, Depth 3Ft-5Ft. Built 1992
    Pentair Whisper Flow Pump 1HP. Winter safety cover w anchors.
    Sand filter, Pentair Sand Dollar Top Mount Model SD80; Effective Filtration Area 3.5SF
    - FlowRate 75GPM, 8Hr 36,000, 10Hr 45,000, 12Hr 54,000; Pressure Weight 50PSI
    BBB (Hayward Chlorinator when leave town). Polaris 360 cleaner.

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    Re: pH of 7.4 or 7.3 ?

    Is everyone estimating pH of 7.4 or 7.3? The pH test that came with my TF-100 has color matches for 6.8, 7.2, 7.5, 7.8 and 8.2. If the color appears to fall between 7.2 and 7.5, do you say that the pH is 7.3 or 7.4 depending on whether it's closer to the 7.2 or 7.5?

    I can easily distringuish between 7.2 and 7.5 (and I can sort of guess when the shade is between the two) but when it gets above 7.5 the shades of red/pink pretty much look the same to me.
    9,200 gal. Gunite Luna Quartz French Grey pool with spill over spa, two fountains on tanning ledge (rarely used)
    Pentair Whisperflo 2HP, Pentair CCP Cartridge 420 Sq. Ft., Polaris 280 with booster pump
    Pentair EasyTouch 4, RayPak LoNox 266k Natural Gas heater, Aqua Rite SWCG T Cell 9, Borates, TF-100 test kit

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    Richard320's Avatar
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    Re: pH of 7.4 or 7.3 ?

    Quote Originally Posted by HouTex
    Is everyone estimating pH of 7.4 or 7.3? The pH test that came with my TF-100 has color matches for 6.8, 7.2, 7.5, 7.8 and 8.2. If the color appears to fall between 7.2 and 7.5, do you say that the pH is 7.3 or 7.4 depending on whether it's closer to the 7.2 or 7.5?

    I can easily distringuish between 7.2 and 7.5 (and I can sort of guess when the shade is between the two) but when it gets above 7.5 the shades of red/pink pretty much look the same to me.
    Yes. With a little practice, you'll be ables to discern if you're closer to 7.5 than 7.3, which makes it 7.4, and so on. I find it helps to hold the test block at arms length with a white background (I use a cheap vinyl stacking chair since it's right there) and sort of squint so it gets a little blurry.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: pH of 7.4 or 7.3 ?

    I've had a ton of practice (everyday for 9 months!) and I think it's still a guess whether I'm closer to 7.2 than 7.5. I really have a hard time with the red/purple of 7.8 and 8.2. The red/purple thing is too close. I don't think I've ever had a purple result.
    9,200 gal. Gunite Luna Quartz French Grey pool with spill over spa, two fountains on tanning ledge (rarely used)
    Pentair Whisperflo 2HP, Pentair CCP Cartridge 420 Sq. Ft., Polaris 280 with booster pump
    Pentair EasyTouch 4, RayPak LoNox 266k Natural Gas heater, Aqua Rite SWCG T Cell 9, Borates, TF-100 test kit

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    Re: pH of 7.4 or 7.3 ?

    in all reality, is there any significant difference between 7.3 and 7.4?
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    Re: pH of 7.4 or 7.3 ?

    Quote Originally Posted by diverman57
    in all reality, is there any significant difference between 7.3 and 7.4?
    Since the scale is logarithmic, the difference is actually larger than it appears. A pH of 7.3 is about 1.26 times as acidic as a pH of 7.4.

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