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Thread: Confused about PH

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    setsailsoon's Avatar
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    Confused about PH

    Folks,

    I've got all of 22 days of TFP pool experience and all is going pretty well... the pool is good on all the numbers and looks great. But I'm a little confused about PH. We get a LOT of rain here in Stuart Florida. For the last couple of days we've had a lot. I've noticed my PH gradually rises so I use 34.5% muratic to control. I searched all over the place on the net and these forums and the general consensus is that it's acidic... makes sense to me with the CO2. But just for the heck of it I tested the rain today. Wow! I get 8.0, double checked with my wife (she detects the red shades better than I do). I also used a calibrated meter and got 8.1. Is Florida rain just different? I'll post my recent test results below. The gap is a 10 day absence (I'm semi-retired consultant so that happens every month or two).

    All comments welcome.

    Best regards,

    Chris

    Date TA CYA FC CC CH PH Actions
    31-Oct-15 130 <20 20 0 225 7.6
    1-Nov-15 130 <20 18 0 225 7.7
    2-Nov-15 100 <20 14 0 225 7.7
    3-Nov-15 90 <20 12 0 250 7.5
    4-Nov-15 90 8 0 7.5
    5-Nov-15 90 7 0 250 7.6
    6-Nov-15 4 7.8 Addded 16 oz muriatic acid 31.45%
    6-Nov-15 80 <20 4 0 275 7.4 6 hr after acid addition
    7-Nov-15 80 <20 2.5 0 300 7.6 Added 1 gal 10% Cl
    8-Nov-15 14 Added .75 gal 10% Cl, 10 oz 31.45 Muratic Acid, 6 oz trichlor
    9-Nov-15 Out of Town
    10-Nov-15 Out of Town
    11-Nov-15 Out of Town
    12-Nov-15 Out of Town
    13-Nov-15 Out of Town
    14-Nov-15 Out of Town
    15-Nov-15 Out of Town
    16-Nov-15 Out of Town
    17-Nov-15 90 20 3.5 0 300 8 added 20 oz 31.45% Muratic Acid
    18-Nov-15 2 7.4
    19-Nov-15 2 7.5 added 8 oz trichlor, tested after 6h w/pump FC 3, Ph 7.5
    20-Nov-15 5
    21-Nov-15 80 20 6.5 0 300 7.7 cut chlorinator back to 0
    -Chris-
    2013 In-ground plaster/pebble, screen enclosed, 12000 gal w/ Jandy 2 speed 1 HP pump, Jandy CS 200 cartridge filter, 800 gal spa w/ 1.5 HP booster pump, Solar heater, 2 LED lights in pool 1 light in spa, TF-100 test kit, The PoolCleaner Next Generation, Jandy RS-12 Automation system with iAqualink 2.0 control, Separate Hayward/Goldline Solar control

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    JoyfulNoise's Avatar
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    Re: Confused about PH

    The rain water's pH has nothing to do with the pH rise of your pool. pH rise in pool water is completely dominated by carbon dioxide outgassing from the water. The chemistry isn't complex but there are a few reactions happening - CO2 outgassed from the pool water then the bicarbonate buffer (the largest component of TA) shifts so that it creates more CO2 in the water. The process of bicarbonate (HCO3-) converting to aqueous CO2 requires the consumption of a proton (H+) and thus increases the measured pH.

    Rain water hitting the surface of your pool causes increase aeration of the water thus increasing the rate of CO2 outgassing. As well, all pool water is over-carbonated compared to atmosphere so there is a natural driving for for your pool water to outgas CO2 constantly. This is why when you cover your pool you can almost totally arrest the pH rise because there is no CO2 outgassing.

    I do believe you that your rainwater has high pH. Rainwater pH can vary quite a bit depending on climatic conditions. However, unless your pool is overflowing with rainwater everyday, the pH of a few inches of rain should make little difference to your 12,000 gallon pool. If rain water dilution was substantial, pH would be the least of your chemical problems as your CYA and CH would be dropping like a stone.

    - - - Updated - - -

    BY the way, your CYA (stabilizer) is quite low. You should increase it up to a minimum of 30ppm. Are you keeping it low over the winter?
    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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    Mod Squad kimkats's Avatar
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    Re: Confused about PH

    I am also in FL and find that a big rain will push my PH up. It is just something we live with so I keep MA on hand to push it back down.

    I use my returns to roll the water if I want to push the PH up if it drops for any reason. It does it quickly so I have to watch it close.

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    setsailsoon's Avatar
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    Re: Confused about PH

    Joyful,

    Thanks so much for the comprehensive response and that makes a lot of sense. This is taking me back about 45 years but I do seem to remember ph = -log[H30]... so less hydroniums means higher PH. TFP chemistry is making more and more sense to this newbie. On the CYA I guess it's the fact that I do get a lot of rain, in two years here I've only added water once. That happened when I returned home and the pool was completely full from rain so I hooked up the hose to a valve downstream of the pump and just left it wide open a couple of days. Bad move... I learned all about letting the level drop too far and sucking air into the pump. But I did finally get to add a little water. Much of the time I have to drain out 3" per week but this time of year we only have to drain an inch every now and then. My FC consumption doesn't seem excessive and I'm guessing that's due to the screened in enclosure that really cuts down on the sunlight and wind on the surface. So I sort of ignored the low CYA while I learned about TFP chemistry and I focused on learning how to control FC with liquid (10%) and control the ph with Muratic. Now that I'm getting confident with that part (maybe overconfident) I'm adding FC with just trichlor until I get CYA up to at least the minimums. While I'm at it I'm now figuring out how to adjust the tablet feeder.... seems to be a little finicky. Once I get the CYA in order I'll switch back to 10% liquid. I really thought handling the gallon jugs would be a pain but I'm finding that it's no big deal to me. And I really like the underlying philosophy I have learned here of adding only what I need. Does this approach make sense to you or should I have a little more urgency about the low CYA?

    Kim, thanks for the reply and I guess between the phenomenon Joyful mentioned plus our 8 pH rainwater we'll be keeping that muratic handy in the deck box. We got at least 2" today in a couple of BIG downpours. Thanks for the advice on small adds of muratic... I was shocked at how quickly it dropped with my last add of 20 oz... I think I'll go half that much next time.

    Thanks to both of y'all for the thoughtful and helpful replies.

    Chris
    -Chris-
    2013 In-ground plaster/pebble, screen enclosed, 12000 gal w/ Jandy 2 speed 1 HP pump, Jandy CS 200 cartridge filter, 800 gal spa w/ 1.5 HP booster pump, Solar heater, 2 LED lights in pool 1 light in spa, TF-100 test kit, The PoolCleaner Next Generation, Jandy RS-12 Automation system with iAqualink 2.0 control, Separate Hayward/Goldline Solar control

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    Mod Squad kimkats's Avatar
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    Re: Confused about PH

    Chris do you have the bleach and MA in the same box?? If you do PLEASE go out right NOW and take the MA out of the box and put it in a different place that is well vented, away from anything that can rust.

    MA and bleach/chlorine do NOT play well together! Well they do if you like things that go boom!

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: Confused about PH

    Hi Chris,
    it seems you are getting the hang of things and learning. It's always nice to see that. Learning is what TFP is all about.

    There is no urgency in getting your CYA up in your situation. And no harm in using the thrichlor tabs and then switch to liquid when you need to.
    Divin Dave,
    IG Vinyl, 15' x 30', 3 1/2' - 6' deep, Oval, ~15K gal, Intelliclor IC40, Intelliflo VS pump, Clean and Clear 420 Filter, auto-fill-disabled, Retrofit LED Color Light, Dolphin Nautilus Robot, TF100 Test Kit, Taylor K1766 Salt Test Kit, Tftestkit Pressure Gauge.
    www.tftestkits.net Experience- it's what's learned just after you needed it most !!

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    setsailsoon's Avatar
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    Re: Confused about PH

    Quote Originally Posted by kimkats View Post
    Chris do you have the bleach and MA in the same box?? If you do PLEASE go out right NOW and take the MA out of the box and put it in a different place that is well vented, away from anything that can rust.

    MA and bleach/chlorine do NOT play well together! Well they do if you like things that go boom!

    Kim
    Kim,

    Thanks!... I had them in opposite end of the deck box but moved the acid to a different container that's well ventilated... I had no idea they'd go boom! If that happened it would be the end of TFP for me... my wife would fire me and call the pool service.

    Thank you sooo much!


    Chris
    -Chris-
    2013 In-ground plaster/pebble, screen enclosed, 12000 gal w/ Jandy 2 speed 1 HP pump, Jandy CS 200 cartridge filter, 800 gal spa w/ 1.5 HP booster pump, Solar heater, 2 LED lights in pool 1 light in spa, TF-100 test kit, The PoolCleaner Next Generation, Jandy RS-12 Automation system with iAqualink 2.0 control, Separate Hayward/Goldline Solar control

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    setsailsoon's Avatar
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    Re: Confused about PH

    Quote Originally Posted by Divin Dave View Post
    Hi Chris,
    it seems you are getting the hang of things and learning. It's always nice to see that. Learning is what TFP is all about.

    There is no urgency in getting your CYA up in your situation. And no harm in using the thrichlor tabs and then switch to liquid when you need to.
    Thanks Dave, It helps to know that y'all think I'm doing OK... well sort of. I think Kim averted a potential disaster with her previous post. That would have been just great... I'm just now getting comfortable with this then boom! If I didn't get anybody hurt I'd have been banned from pool care for life. Thanks again Kim!

    Chris
    -Chris-
    2013 In-ground plaster/pebble, screen enclosed, 12000 gal w/ Jandy 2 speed 1 HP pump, Jandy CS 200 cartridge filter, 800 gal spa w/ 1.5 HP booster pump, Solar heater, 2 LED lights in pool 1 light in spa, TF-100 test kit, The PoolCleaner Next Generation, Jandy RS-12 Automation system with iAqualink 2.0 control, Separate Hayward/Goldline Solar control

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    Divin Dave's Avatar
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    Re: Confused about PH

    Good deal Chris,

    You're coming along fine, and I applaud you for not trying to bite off more than you can chew with regards to learing the chemistry. No need to make the learning curve steeper than it needs to be. Right?

    I dont think Kim literally meant they will go boom. If there were to be an accidental spillage of both, and they mix, it won't explode. What hapens is that toxic chlorine gas is created and it's very dangerous. So, its always a good idea not to store them in close proximity for that reason.

    if you do happen to accidentally mix them, and see a green or brown gas cloud rising....run upwind.
    Divin Dave,
    IG Vinyl, 15' x 30', 3 1/2' - 6' deep, Oval, ~15K gal, Intelliclor IC40, Intelliflo VS pump, Clean and Clear 420 Filter, auto-fill-disabled, Retrofit LED Color Light, Dolphin Nautilus Robot, TF100 Test Kit, Taylor K1766 Salt Test Kit, Tftestkit Pressure Gauge.
    www.tftestkits.net Experience- it's what's learned just after you needed it most !!

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    Mod Squad kimkats's Avatar
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    Re: Confused about PH

    Okay so not go boom (I had no idea what it would do but knew it was bad to mix them) but toxic gas.......SCARY!

    Good job moving them away from each other.

    You are doing an awesome job learning. How are things going today? How does your pool look?

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: Confused about PH

    Kim,

    Boom or not I had them way too close and spill could have happened with very bad results. I made the change right after I read your post and I've told my wife about the mistake that a very smart pool lady warned me about.

    Thanks for the follow-up and encouragement. The pool is looking great! Yesterday I vacuumed as it had been 3 weeks! The enclosure we have helps keep the dirt to a minimum but I had these ugly brown patches that must be very light dust. When I wave the brush over top of it it sort of looks like a miniature dust storm about 6" high off the bottom. Can't imagine where that comes from but there is still a good bit of construction around here. Anyway the pool looks better than ever!

    Chris
    -Chris-
    2013 In-ground plaster/pebble, screen enclosed, 12000 gal w/ Jandy 2 speed 1 HP pump, Jandy CS 200 cartridge filter, 800 gal spa w/ 1.5 HP booster pump, Solar heater, 2 LED lights in pool 1 light in spa, TF-100 test kit, The PoolCleaner Next Generation, Jandy RS-12 Automation system with iAqualink 2.0 control, Separate Hayward/Goldline Solar control

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    Mod Squad kimkats's Avatar
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    Re: Confused about PH

    It could be dead algae. It sounds like you caught it right in time!

    Have you done a OCLT in a while? I do one at least once a month if not every other week just to keep an eye on things. I posted the link just in case you did not have it on hand.

    Pool School - Perform the Overnight FC Loss Test (OCLT)

    Got to keep that Florida pool pretty! We have to represent!

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: Confused about PH

    Kim,

    Wow, I haven't done an OCLT yet so I'll check. Sounds like a good thing to add to my testing as well. I'd sure hate to have an outbreak now. I have a consulting gig coming up in Texas and will have to leave the pool untreated for 5 days next Sunday so I want it to be in great shape before I leave.

    Thanks for the help again!

    Chris
    -Chris-
    2013 In-ground plaster/pebble, screen enclosed, 12000 gal w/ Jandy 2 speed 1 HP pump, Jandy CS 200 cartridge filter, 800 gal spa w/ 1.5 HP booster pump, Solar heater, 2 LED lights in pool 1 light in spa, TF-100 test kit, The PoolCleaner Next Generation, Jandy RS-12 Automation system with iAqualink 2.0 control, Separate Hayward/Goldline Solar control

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    Mod Squad kimkats's Avatar
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    Re: Confused about PH

    Is your wife on board to adding the bleach while you are gone? She does not have to test if she does not want to but it would be better if she learned how.

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: Confused about PH

    Kim,

    Great news, my wife Robin has agreed to do some of the simple tests while I'm away.

    Keeping to the subject of this thread we've also found a way to hone our color test accuracy for pH. I bought a highly rated but very inexpensive meter and also bought some pre-mixed calibration fluid. I'm finding with this as our back-up we're getting pretty good at pH... the calibration is a pain and not something I want to do long term but it's a pretty cheap tuition so we can confidently rely on the color test long term. I'm also realizing we weren't all that bad before. I was off by a max of .2 and Robin was off no more than .1... I guess it's a female thing.

    Again, many thanks for all your help.

    Chris
    -Chris-
    2013 In-ground plaster/pebble, screen enclosed, 12000 gal w/ Jandy 2 speed 1 HP pump, Jandy CS 200 cartridge filter, 800 gal spa w/ 1.5 HP booster pump, Solar heater, 2 LED lights in pool 1 light in spa, TF-100 test kit, The PoolCleaner Next Generation, Jandy RS-12 Automation system with iAqualink 2.0 control, Separate Hayward/Goldline Solar control

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    Re: Confused about PH

    Just a note, I see you have a spa on your pool as well. My own pH increases when we run our waterfall, as the water aerates. Our central FL rain seems to increase pH as well. Just our observation, maybe the spa bubbling is helping increase the pH as well.

    Just my 2 cents
    Phil
    ~9600 gal gunite pool, NEW July 2015; Pentair Intelliflo 2 VST pump; Pentair C&C 150 filter; Pentair Intelliclor IC40 swg; solar heat w/ Pentair Solartouch controller, screened. Taylor K 2005 test kit, FAS-DPD separate test, Taylor K1766 salt test

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    Re: Confused about PH

    Yeah, guys only recognize about 8 colors!
    18'x38' Rectangle (3'-8 1/2' deep w/ diving board) - 27K gal. w/ gray plaster
    Hayward equipment (cartridge filter, 2-speed pump, SWCG, automation) View Our Build
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    JoyfulNoise's Avatar
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    Re: Confused about PH

    Quote Originally Posted by flipr View Post
    Just a note, I see you have a spa on your pool as well. My own pH increases when we run our waterfall, as the water aerates. Our central FL rain seems to increase pH as well. Just our observation, maybe the spa bubbling is helping increase the pH as well.

    Just my 2 cents
    Yes, this is quite common and your intuition is correct. The bulk of your water's alkalinity comes from the bicarbonate anion (HCO3-). When you aerate the water, whether by spa jets, waterfalls, bubblers, spillways, etc, you force dissolved CO2 out of the water. Dissolved CO2 will also just naturally outgas as pool water is over-carbonated relative to atmospheric CO2. When the dissolved CO2 leaves the water, the bicarbonate behaves according to the following chemical reactions -

    CO2(aq) + H2O <---> H+ + HCO3(-)

    (Dissolved CO2) + (Water) <---> (acid proton) + (aqueous bicarbonate)

    So the bicarbonate reacts with an acid proton to form water and aqueous CO2, i.e., the bicarbonate is trying to restore the balance of the CO2 lost from aeration. Since the reaction consumes a hydrogen ion, the pH goes up.

    Almost all pH rise in pool water can be attributed to outgassing of CO2 from the water. If you turn off, or greatly reduce your aeration sources, and cover your water with a simple pool cover, you will see the pH in your water rise much more slowly than when it is uncovered.
    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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    Mod Squad kimkats's Avatar
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    Re: Confused about PH

    good news all around! Hi Robin!! You can do it! Good job on finding a way to make sure you can read the PH colors. Of course SHE (being a female) did better! LOL

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    setsailsoon's Avatar
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    Re: Confused about PH

    Folks,

    Thanks for all the great replies! The aeration makes a lot of sense. Water returns to the spa and then through two overflows to the pool all the time the pump runs. I run it from 9 am to about 5 pm to take advantage of the solar heating so I'm doing a lot of aeration. Joyful, I'm still trying to follow the water chemistry... so what happens to the H+ that is liberated? Does it combine with dissolved O2 until a new equilibrium is achieved... I guess there's a plentiful supply with my aeration. Sorry for the dumb water chemistry questions it's just been a LONG time and never was my strong suit.

    Kim, next time I get the brown stuff on the bottom I'll try to get a sample and look at it under my old college microscope (if it still works). Pollen should be easy to spot and Robin says Hi back! and she naturally agrees...

    Thanks again for all the replies.

    Chris
    -Chris-
    2013 In-ground plaster/pebble, screen enclosed, 12000 gal w/ Jandy 2 speed 1 HP pump, Jandy CS 200 cartridge filter, 800 gal spa w/ 1.5 HP booster pump, Solar heater, 2 LED lights in pool 1 light in spa, TF-100 test kit, The PoolCleaner Next Generation, Jandy RS-12 Automation system with iAqualink 2.0 control, Separate Hayward/Goldline Solar control

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