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Thread: why does acid kill both Ph and alkalinity

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    why does acid kill both Ph and alkalinity

    yesterday... my PH was 8 after adding the borax the night before... my cya count was up too.. ..which is what I wanted... .my Alkalinity was close to 200.. so added muratic acid.. .brought the alkalinity down to 140 cool.. but now my ph is right back to 6.4.. and my CYA count is now back to 0.. is this right... I know I have to get the suggested testers.. will have to order one soon.. .

    and last night i dumped in the suggested amount of clorine(walmart) from Pool Calculator... was at or above 20 on FC... this morning .5

    now from what im reading I have to keep shocking..to keep it around 3-5 I did another shock this morning.. .ill test at noon ..... left cover on ..... all night and today...
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    Ohm_Boy's Avatar
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    Re: why does acid kill both Ph and alkalinity

    I'm a little confused by your post. Any additional information you could give would help, starting with a full set of test numbers, how the water looks, and any special conditions - are you just opening? big party last night? etc..

    1) Yes, acid affects both PH and Alkalinity.
    In fact, ph is a measurement of the concentration of hydrogen ions, or how 'acid' or how 'alkaline' your water is. Low numbers indicate acidity, high numbers indicate alkaline or 'basic', with 7 being neutral. Typically you want to be in the 7.2 to 7.6 range. "Total Alkalinity", as it refers to a pool, is a measure of the carbonate buffer, which helps to stabilize the ph of the water. High TA tends to 'pull' the ph up, while low TA allows the ph to vary easily and let it be erratic. PH and TA are related. Since you have lowered both your ph and TA with acid, you can raise the ph by aerating the water, which will allow carbon dioxide to offgass and the ph will rise. You may be able to turn on a fountain or water feature to aerate, or maybe even point a return 'eyeball' up so that the water jet breaks the surface of the water. Any surface turbulence should help. Borax will also raise the PH without affecting the TA much.

    2)CYA - something is wrong here. CYA typically does not go away, so if it was up, and you haven't replaced water, then it shouldn't drop to zero. CYA measurements can sometimes be inexact, and I usually suspect testing errors first, but if it is really dropping, it could also be an indicator of ammonia.

    3) Chlorine... You say that the poolcalc recommended (and you adjusted to) a level of 20? And it was down to 0.5 by morning? That is a really heavy chlorine demand, and is another pointer to ammonia.
    Also, if the calculator is recommending 20, why would you be trying to get 3-4?
    [center:1kpalu48]Helpful Links: Pool School | CYA/Chlorine Chart | Pool Calculator[/center:1kpalu48]

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    Re: why does acid kill both Ph and alkalinity

    Get a inexpensive ammonia test from a pet store and test your water. That would remove any doubt about amminia in the water. How are you testing your water, what kind of test kit etc. ? Sorry if there are more questions than answers but we need more data.
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    Re: why does acid kill both Ph and alkalinity

    Yes I did do the ammonia test the other day... read Ideal.... this is a continuation post from my walmart stabalizer ok to buy....

    the aim for 20 is the initial shock.. recomendations from pool calculator. my CYA read 30-50 so i did enough clorine to get to the 20 read on the meter... worked just fine..in one hour was 20+. i thought i read somewhere on here that you should try to always keep clorine levels for 3-6.....so i gave some more clorine before work and at lunch was 5.6....
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    Ohm_Boy's Avatar
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    Re: why does acid kill both Ph and alkalinity

    I went back to see your other post - and I can see a bit more about your situation.
    First and foremost, you are testing your water with test strips. I have seen them be so extremely inaccurate that in most cases, I simply disregard the test numbers completely. They are poor to useless when new, and get worse with age. Regardless of whether you compare the strips with a color chart to get a reading, or stick it into a meter to have it guess what the color means, the results are rarely precise or accurate. Personally, I would trust a small 5 or 6-way test kit from Wal-Mart over strips, though they still cannot read high chlorine (anything over 5). If you cannot get your hands on a good test kit, you should have a pool store test your water and post the numbers here. Try to avoid results like "low", or "in range"... we want actual test result numbers. Yeah, we're picky that way. Make sure that ph and calcium hardness (CH) are included.

    Next, you said in your other thread that there were leaves in the pool from the cover removal? Did all of this get cleaned out? Any organic gook in the pool will consume chlorine like Jughead eating burgers.

    Then we can address shocking. As you are reading in the Pool School section, shocking is a process, not a one-time action. The concept is to raise the chlorine level high enough to kill the nasties in the pool. It gets 'used up' by doing this, so as it works, it goes away. In severe cases, the chlorine gets used up almost as soon as it is introduced. You will need to raise the level to the recommended shock point, monitor the level, and add chlorine as needed in order to keep it there. It's like taking an antibiotic - you can't just take one pill and be done, you have to keep the dose up until it 'wins'.
    [center:1kpalu48]Helpful Links: Pool School | CYA/Chlorine Chart | Pool Calculator[/center:1kpalu48]

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    Re: why does acid kill both Ph and alkalinity

    Scott, I'm sorry to be so repetative, but you need a good drop based test kit, as previously suggested. Between the MA, bleach and borax swaying your #'s all over the place you are wasting money on chemicals that are not needed. This is why we advocate investing in a test kit...in the long run it will save you $
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    Re: why does acid kill both Ph and alkalinity

    ohm boy its starting to make sense.... I always thought it was a one shot deal.. I get confused very easy...this actually raises more questions in my head....

    I failed to mention.. that actually Im doing test stripes,digital meter and the 6 Hth drop test kits... all showing the pretty much same results

    k here goes..

    so the clorine I put in was pretty much a waste (again) of money and time and trips to walmart

    so Im guessing that this could be an all day process?
    how does a working guy(8hours a day)... do this whole process?
    I thought the best time to add clorine was at nighttime...???
    Ok... last night i did 6 gallons of clorine... if I do shock .. measure each hour... and starts to drop.... im looking at a ton of clorine.. wonder if walmart delivers..
    20000 gallons of water any idea what this whole process will take
    If i start on an early saturday morning.. could this take all day and night..?
    Ok .my brain is fried... .maybe I should do like my buddy.. 1 shock package once a week and puck floater..crystal clear,,and he never tests his water.... ... thanks scott
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    Re: why does acid kill both Ph and alkalinity

    Quote Originally Posted by scott6824
    Ok .my brain is fried... .maybe I should do like my buddy.. 1 shock package once a week and puck floater..crystal clear,,and he never tests his water.... ...
    Trichlor pucks/tabs are very acidic so if your friend never tests his water, not even pH, then eventually the TA will get to zero and the pH will crash below 4.5 risking serious damage to his equipment (and plaster or vinyl). So even if he is lucky enough not to get algae as the CYA level rises, not checking on pH is asking for trouble.
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    Re: why does acid kill both Ph and alkalinity

    Quote Originally Posted by scott6824
    Yes I did do the ammonia test the other day... read Ideal....
    Is "ideal" zero? I'm not sure about aquariums, but for pools there needs to be zero.
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    Re: why does acid kill both Ph and alkalinity

    Quote Originally Posted by chem geek
    Quote Originally Posted by scott6824
    Ok .my brain is fried... .maybe I should do like my buddy.. 1 shock package once a week and puck floater..crystal clear,,and he never tests his water.... ...
    Trichlor pucks/tabs are very acidic so if your friend never tests his water, not even pH, then eventually the TA will get to zero and the pH will crash below 4.5 risking serious damage to his equipment (and plaster or vinyl). So even if he is lucky enough not to get algae as the CYA level rises, not checking on pH is asking for trouble.

    not to mention the water will be extremely unsafe for swimming!
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    Re: why does acid kill both Ph and alkalinity

    Quote Originally Posted by scott6824
    yesterday... my PH was 8 after adding the borax the night before... my cya count was up too.. ..which is what I wanted... .my Alkalinity was close to 200.. so added muratic acid.. .brought the alkalinity down to 140 cool.. but now my ph is right back to 6.4.. and my CYA count is now back to 0.. is this right... I know I have to get the suggested testers.. will have to order one soon.. .

    and last night i dumped in the suggested amount of clorine(walmart) from Pool Calculator... was at or above 20 on FC... this morning .5

    now from what im reading I have to keep shocking..to keep it around 3-5 I did another shock this morning.. .ill test at noon ..... left cover on ..... all night and today...
    check into the kits listed here on the site. http://www.troublefreepool.com/pool-...kit_comparison
    he test strips and digital reader really shouldn't be used for making adjustments, just quick checking for "ok" levels.
    the 6 drop you picked up is a simple introduction to pool testing.
    are you pulling samples while the pool is circulating? your last set of results seem indicative of a sample that might of been taken while the pool was turned off.
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    Re: why does acid kill both Ph and alkalinity

    just got to thinking you are correct ... my mistake,,,,, didn't even think about the pump running.. ill be more cosistant(even better when i get my new test kit)

    Ed can you answer some of my shock questions
    like just how long is this shock process take... I wll have to try a saturday... all day
    and just how many gallons on a 20000 gal pool with just a bit of algae....
    thanks
    20000 gal. 28' round
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    3.5 and 6 deep
    22" round meteor sand filter
    tf-100 test kit

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    Re: why does acid kill both Ph and alkalinity

    Like others have said the test strips are nearly useless (maybe worse than useless depending on your viewpoint), I tried them myself a couple of summers ago when the local places were all out of real drop based kits and I needed a way to check the water. I quickly found the 5 or 6 way test strips I had bought were not only hard to read, but sometimes very inconsistent giving wildly different readings on test strips used just minutes apart. Additionally the resolution of some of the measurements is so crude as to at best get a very large ballpark reading, some so large as to span the recommended level spread such as the one for calcium hardness.

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    Re: why does acid kill both Ph and alkalinity

    folks... please.. I know I have to get a better test kit... enough... as stated previously Im doing 3 methods... digital,6way drop test, and test stripes.. all these are showing the same thing..a new test kit will be on order soon..

    just really looking at some advice on shocking the pool... thank you
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    Re: why does acid kill both Ph and alkalinity

    The best way to shock is to find several hours in a row, it doesn't need to be all day, and check and add chlorine hourly for a couple of hours to start. After that you can slow down to two or three times a day. If you take too long of a break between chlorine additions you are losing ground to the algae, so about 12 hours between chlorine additions is about the longest you should let it go.

    How long the entire process will take and how much total chlorine it will use is difficult to predict. It depends on how much time you have to devote to it, how much algae there is, and how good your test kit is. With inferior test kits, you need to add more chlorine and continue shocking longer to be sure that you got all of the algae.
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    Re: why does acid kill both Ph and alkalinity

    Quote Originally Posted by scott6824
    just got to thinking you are correct ... my mistake,,,,, didn't even think about the pump running.. ill be more cosistant(even better when i get my new test kit)

    Ed can you answer some of my shock questions
    like just how long is this shock process take... I wll have to try a saturday... all day
    and just how many gallons on a 20000 gal pool with just a bit of algae....
    thanks
    It really depends on how much organic material is in your pool and how consistently you keep the pool at shock level. If the pool is cloudy you may be able to clean it up in a couple of days. If it is a swamp, green or black and you can't see the bottom of the pool anywhere it can take a week or more (often more).

    Since you have all day Saturday, stock up on bleach, start with a shock dose Friday night and let the pump run 24/7 until you are done. Get up early Saturday, test the water and bring it back to shock level. Test again in about an hour and bring the pool back to shock level. Wait another hour, test again, bring back to shock level. If you are seeing drops in FC of 3ppm or more every test then continue to test the water and bring to shock level every hour. When the FC starts to hold a little longer you can wait 2 hours between tests.

    Be sure you clean your filter as needed during the shock process. When the pressure rises 8-10 lbs or the return flow is diminished you will need to clean the filter.

    As far as how many gallons of bleach it will take, I can't really say, every pool is different. Buy about 20 jugs, make sure it is 6% or stronger. Make sure you enter the correct jug size and strength in the pool calculator when calculating how much bleach you need.
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    Re: why does acid kill both Ph and alkalinity

    this is the info I was looking for... pool is really pretty clear.. little bit of algae by the rinkles in the liner....

    thanks again...I have about 12 gallons of bleach so far... ... walmart is out waiting for restock...
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  18. Back To Top    #18
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    Re: why does acid kill both Ph and alkalinity

    If you really want to beat this, don't wait for WalMart to restock. Go get your bleach somewhere else or you are just wasting time. Paying a little more somewhere else will get you the results you are looking for, but waiting for Wally World is only going to prolong the agony

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    Re: why does acid kill both Ph and alkalinity

    Quote Originally Posted by scott6824
    just got to thinking you are correct ... my mistake,,,,, didn't even think about the pump running.. ill be more cosistant(even better when i get my new test kit)

    Ed can you answer some of my shock questions
    like just how long is this shock process take... I wll have to try a saturday... all day
    and just how many gallons on a 20000 gal pool with just a bit of algae....
    thanks

    Sorry I didn't chime in sooner. I'm not one to suggest the liquid chlorine method so I'm the wrong person to ask on that one...looks like everyone else that jumped in has it pretty well covered.

    You might also see:


    http://www.poolcalculator.com/

    I was playing with this yesterday...pretty cool
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    Re: why does acid kill both Ph and alkalinity

    like just how long is this shock process take... I wll have to try a saturday... all day
    and just how many gallons on a 20000 gal pool with just a bit of algae....
    thanks
    Often asked. Unfortunately, the answers to both are blurry. The process can take from 24 hours to a week,,,,,generally depending on how much junk is in your pool and how willing you are to dedicate yourself to it.

    The bleach answer is blurry, too. 10 gallons is seldom enough (but it can be) and I'm not sure what the record is but I know folks have reported usage of over 100 gallons.

    Read the article in Pool School and have a thorough understanding of the process before you start....it'll make it go much quicker.
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