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Thread: What can cause PH to shoot up?

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    What can cause PH to shoot up?

    I tested yesterday or the day before and PH was around 7.4 or so. I have just been using my SWG. FC around 3.0. I test today and PH is like 8.4. What could cause that? I belive the SWG can cause PH to move up, but this seems a bit extreme?
    12000 gal diamond brite pool with 400 gal spillover spa, 1 1/2 HP pump and Hayward 1100 cartridge filter, Hayward Heatpump.

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    Hi, Rob,

    Look in the deep end of the pool and see if the Borax delivery truck didn't make the turn and ended up in the bottom of your pool!! (Sorry)

    I would suspect the testing chemistry or testing method. I can think of no circumstance where an overnite occurence like that makes sense.........short of something being spilled in it.
    Dave S. - Forum owner
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    The testing method is test strips. I know they aren't perfect, but I do know when I test and its high and I dump in acid, it drops right down, so they are relatively accurate.
    12000 gal diamond brite pool with 400 gal spillover spa, 1 1/2 HP pump and Hayward 1100 cartridge filter, Hayward Heatpump.

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    With high TA levels, anything that causes aeration, rain, kids splashing, etc, can cause the PH to shoot up. Fresh plaster can raise PH very quickly as it cures. Rarely, airborne dust that is very basic, sometimes from construction sites, and can cause PH to rise. A SWG causes some aeration which will raise PH, but that should be fairly consistent.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Test strips are accurate but they are not precise, particularly the pH test. The calibration of the small color differences are very large so just a slight error in reading will produce a large change in what you think the pH is. Also, how long the test strip sits before you read it has an impact on color development. Even a cheap 2 way tester that uses phenol red for pH testing will provice more precise pH results than strips are able to.

    In terms of pH rise from a SWG, several factors come into play here:
    Your CYA level (which affects cell output, which afffects aeration of the water and outgassing of carbon dioxide)

    Your TA (high TA causes the pH to want to rise faster than a lower TA. This is a benefit when using acidic chlorine sources like trichlor and dichlor but works against SWGs and unstabilized chlorine sources, which do better with a much lower TA--say between 70-90 ppm)

    Your pH! Lower pH will produce a faster outgassing of carbon dioxide than a higher pH, therefore a faster pH rise. My recommendation for SWGs and pools chlorinated with unstabilized chlorine such as bleach or cal hypo is to adjust your pH to 7.6 and no lower and when the pH climbs to 7.8 add acid to lower it back down to 7.6 and no lower. This is not hard to do with a bit of trial and error and an ACCURATE and PRECISE drop based pH test! This will minimize your acid usage. I have seen this happen time and again in my customer's and my own pool!

    Hope this helps!

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    TA is around 120. I never seem to have any luck getting it lower. I do have a jacuzzi with a waterfall that is always running and also two lions heads that shoot water out of their mouths. I am assuming this is causing the rise in PH. I understand from reading here that dropping the PH down and then aerating as my pool always does should be dropping my TA'?
    12000 gal diamond brite pool with 400 gal spillover spa, 1 1/2 HP pump and Hayward 1100 cartridge filter, Hayward Heatpump.

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    Yes, if you have the aeration and add acid, then the TA will drop but does so rather slowly over time. To accelerate the process, you can intentionally lower the pH closer to 7.0 (which takes a lot of acid to do) and then aerate at that lower pH. That makes the tendency for the pH to rise very strong so you aerate and add acid at the low pH and the TA will drop much more rapidly. The procedure is outlined in this post at The Pool Forum. This post of mine has a table that shows why this works and describes the procedure. Just note that it takes a lot of acid to move the TA any great degree and it will take the same amount of acid whether you slowly reduce the TA or do so more quickly with the procedure. The procedure just gets it over with more quickly so that from that point on the pH is more stable and the amount of acid that needs to be added if far less.

    If you have a lot of evaporation (not likely this time of year) and your fill water is high in TA, then that will increase TA over time. This is the situation in my pool during the summer since it's pH is very stable and I rarely add acid, yet I do notice the TA increase (slowly) because the fill water has a TA of 80 ppm.

    Richard
    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
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    so knowing that ph tests may not be that accurate and such. If I have around a 14000 gallon inground pool and the PH was around 7.6, how much acid are we talking to get it to around 7.0? I usuallyjust pour some from the bottle into the pool, always worried it might be too much. With people talking about a lot of acide, are we talking the whole bottle?
    12000 gal diamond brite pool with 400 gal spillover spa, 1 1/2 HP pump and Hayward 1100 cartridge filter, Hayward Heatpump.

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    The answer depends on your TA level, but with a TA of 100 (and CYA of 40) it would take 51 fluid ounces of Muriatic Acid (31.45% Hydrochloric Acid) in 14,000 gallons to lower the pH to 7.0. If the TA were 150 ppm, it would take 73 fluid ounces. If the TA were 70 ppm, it would take 38 fluid ounces. If your CYA level is higher, say 80 ppm, then starting at a TA of 100 would take 60 fluid ounces to get from a pH of 7.6 to 7.0.

    When I said it takes the same amount of acid to lower the TA, that means the total amount for the entire process, not the amount needed to get to a specific lower pH for the first step.

    The total amount of acid that will be needed during the entire aeration and acid addition process to lower the TA from 150 to 80 is 250 fluid ounces (in 14,000 gallons). To lower from 120 to 80 it takes 143 fluid ounces. To lower from 100 to 80 it takes 72 fluid ounces. That should give you a rough idea of how much acid will be needed depending on your situation (you didn't say what your current TA level is).

    When adding acid, especially when you haven't done this a lot, it is best to add half the calculated amount (for each step) and remeasure pH after at least 30 minutes or an hour (with the pool pump running and good circulation) and see where you are at.

    Richard
    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
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    I said in a post after the first one that the TA is around 120. I should have said it at the top, sorry.
    12000 gal diamond brite pool with 400 gal spillover spa, 1 1/2 HP pump and Hayward 1100 cartridge filter, Hayward Heatpump.

  11. Back To Top    #11
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    IF you get a Taylor K-2006 it includes acid and base demand tests. While these tests are not foolproof they will give you a guide of about how much acid you will need to lower the pH by a given amount (the amount needed varies with the TA. Higher TA will require more acid than lower TA). I usually don't recommend using these tests since they are a guide at best but they can be useful in certain circumstances. The TFTestkit does not include the acid and base demand tests but since it contains more CYA reagent, an OTO chlorine test for quick checks of chlorine level and a wider range pH tester (very useful when trying to lower TA!) I feel it is a better value for the money than the K-2006.

    Also, if you measured your TA using strips they just do not have the resolution you need to adjust it properly. Most strips have a resoluton of 40 ppm for the TA test. This is just too big to be useful for anything! (especially when you consider that the 'sweet spot' for TA with a SWG is about 20 ppm wide!)

    Bottom line, a good test kit will make the process much easier. Strips just don't cut it! When you think of all the money you spent on the pool is about $70 really a lot for a GOOD test kit?

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    its not the money, strips are just so much easier than starting with the chemicals. I had a chemical test kit and stopped using it.
    12000 gal diamond brite pool with 400 gal spillover spa, 1 1/2 HP pump and Hayward 1100 cartridge filter, Hayward Heatpump.

  13. Back To Top    #13
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    Quote Originally Posted by robl45
    its not the money, strips are just so much easier than starting with the chemicals. I had a chemical test kit and stopped using it.
    There is no question that the strips are easier but they are not providing accurate information which makes the task of water balancing much more complicated than it has to be! Also, a good test kit is much easier to use than a cheap one. The strips are good for a quick check to make sure your water parameters are in line but if they are not you should use a drop based test for balancing. Also, there are some inherent drawbacks to strips. They don't test calcium hardnes but total hardness. This is not really a valid test for water balancing. CYA tests of different brands of strips will give very different results on the same sample ( if you don't believe me buy a few different brands and try them!)

    From my own experience with strips I have found the Taylor (and HTH, whch are rebranded Taylor Strips) to be the most dependable. The AquaChek Select and LaMotte 6 way run a distant second and third, IMHO.

    Without accurate and precise test results you are really just guessing on water balance issues. Strips do have a place but that is for a quick check of water parameters and the only parameter on strips that I really trust for this is the chlorine tests. Even those don't seem to be as accurate as the cheapest drop based two way tester, however! I would not depend on strips for pH, TA or Calcium Hardness (which they cannot do!)

    It's your pool and you can test it any way that you want but there are a lot of people here besides myself that will back up what I say. If you want a 'Trouble Free Pool' then it starts with accurate and precise water testing! I looked over some of your other posts and you seem to have a a series of water balance issues and and algae outbreak. I think this alone makes a good case for using a good test kit instead to strips!

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    Hey, Rob,

    What Evan just posted is dead on the money. I understand that drops-based tests are troublesome but you get such a better idea of where your pool water is or how to get it where it needs to be.

    Of course, you have to balance what I say because I sell a drops-based kit but my primary reason for doing so (making the kit) initially was because it was such a good tool for me when I first opened my pool. I would've been lost without mine and the accuracy you get is incredibly helpful....particularly if you have a water issue to solve.

    I'm only parroting (and poorly, at that) what Evan has already said but I want to reinforce his words. Whether you get mine or the Taylor K-2006 I really think it's the best money you'll ever spend on your pool....it was for me.
    Dave S. - Forum owner
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    TFTestkits , PoolMath , Pool School

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    so I got the T/A down, its around 40-80 now. My PH is not shooting up so fast, but is rising. Today its around 7.8. I put more acid in. But isn't my T/A just going to continue to fall?
    12000 gal diamond brite pool with 400 gal spillover spa, 1 1/2 HP pump and Hayward 1100 cartridge filter, Hayward Heatpump.

  16. Back To Top    #16

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    How did you reduce T/A?
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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  17. Back To Top    #17

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    robl45,

    The TA will only continue to fall if you continue to add acid due to the pH rising. This slows down until you get to a point of low TA and higher target pH (say, 7.7) that has the carbon dioxide outgas so slowly that you barely notice the pH rise. This might mean a TA as low as 50 or so with a low CYA of 30 or a TA of 70 with a CYA of 60-80 which is still enough for pH buffering so long as you use a hypochlorite source of chlorine such as bleach or chlorinating liquid (or even Cal-Hypo) or an SWG (as in your case) and not an acidic source such as Trichlor.

    With the test strip only giving you an approximate value of 40-80, it's hard to know where it's at. Also keep in mind that pH and TA move together so if you measure your TA when the pH is lower you'll measure a lower value than when the pH is higher.

    Since the test strips are so rough in their measurement, I'd hesitate having you lower the TA that much more. If you used a drop-based test kit for accuracy then lowering the TA more would be safe to do since you can ensure not going too low.

    Finally, there are other methods that can also help reduce the rate of pH rise. Adding 20 Mule Team Borax to get to a 50 ppm Borates level can act as a pH buffer and as an algaecide to let you lower your SWG output because not as much chlorine will be needed to fight (non-visible) algae growth. But first try and get your TA and pH to a level where the rate of pH rise is lower and see how that works for you.

    Richard
    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
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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