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Posts posted by quantumchromodynamics

  1. Shocking and filtration should resolve the sulfur issue.

    Note: Some pools use an alternative sanitizer called Baquacil. If the previous owners used Baquacil, then you cannot shock with chlorine or MPS (unless you decide to do a full conversion).

    You should ask the previous owners if they ever used Baquacil. If the previous owners are not available, you could have the water tested for Baquacil at the local pool store. Also, what chemicals did the previous owners leave for you? Did they leave any test kits?

  2. I would try to keep the CSI between -0.3 and -0.1. Your numbers are pretty good right now. I think that if you started to use a pH of 7.8 or 7.9, your pH would be more stable.

    The right TA is going to depend on where you want to keep the pH. The lower you want to keep the pH, the lower you need to keep the TA to maintain a stable pH. A pH of 7.8 to 7.9 should be stable with a TA of 60 ppm. If you wanted to use a pH of 7.5 or 7.6, then you will probably need to use a TA of 50 ppm.

    Once you get the pH and TA stable, then you want to adjust the Calcium to where you get in the -0.3 to -0.1 range.

    The offgassing of carbon dioxide causes the pH to rise. The rate of offgassing depends on factors such as temperature, aeration and the concentration of carbon dioxide. This chart shows the concentration of carbon dioxide in ppm at various pHs and TAs (TA as carbonate alkalinity).

    .......................................................TA 100...TA 80....TA 60....TA 50

    pH..........X........%CO2....%HCO3.... CO2........CO2.......CO2......CO2






    There is the same amount of carbon dioxide dissolved in the water at the following:

    pH = 7.5 and TA = 50

    pH = 7.7 and TA = 80

    pH = 7.8 and TA = 100


    pH = 7.6 and TA = 50

    pH = 7.8 and TA = 80

    pH = 7.9 and TA = 100

    Increasing the pH by only 0.3 will allow you to maintain a TA of about 50 ppm higher with about the same amount of stability. Every 0.1 increase in the pH corresponds to an increase in TA of about 17 ppm for the same stability.

    I think that you will begin to see good stability at a carbon dioxide concentration of about 2 ppm or less, such as pH =7.7 and TA =50, or PH = 7.9 and TA =80. However, this is still above the Henry's law concentration of aqueous Carbon dioxide, which is 1.2 x 10^-5 mole per liter at 25 C (77 F), which equals 0.528 ppm.

    Chem geek has a chart here that shows a similar thing.

  3. Every few days, I need to bring the pH down a few points. Maybe next time I fill I will try for CH 100, FC 80 and see if that is more stable.

    I think that you mean CH 100 and TA 80?

    You don't want a higher TA; a higher TA will cause more pH rise. To reduce pH rise, you can use a higher pH and a lower TA. Using a pH of 7.6 to 7.9 and a TA of 40 to 70 should give good stability.

    Right now, you could increase your borates to 50 for more pH buffering. You could also target a slightly higher pH of 7.8 to reduce pH rise. If you increase your borates to 50 ppm, then you could target a pH of 7.9.

  4. The chunks could be calcium carbonate. What do the chunks look like? What do they feel like? Try putting them in some vinegar to see if they will dissolve.

    What are all of your chemical readings?

    Free chlorine

    Combined chlorine


    Total alkalinity


    Cyanuric acid


    Note: Swirl Away contains surfactants, trisodium phosphate, tetrasodium iminodisuccinate and sodium bicarbonate.

    Ingredients.................................... CAS#................ Wt%....... ACGIH-TLV

    SURFACTANT BLEND............... NAV............... 3 - 7............ NONE

    TRISODIUM PHOSPHATE....... 7601-54-9......... 3 - 7........... NAV


    TETRASODIUM SALT........... 144538-83-0....... 3 – 7............. NAV

    SODIUM BICARBONATE..... 144-55-8.............. 5-10............. NAV


    [edit]The link for the MSDS might not work. Possibly a temporary issue?[end edit]

  5. Any sulfur in the water that would cause a "sulfur smell" would be in the form of H2S (hydrogen sulfide), which is in equilibrium with the hydrogen sulfide anion HS-

    (pKa H2S = 7.00). Any hydrogen sulfide should have been oxidized to sulfur or sulfate if the pool has been treated with chlorine.

    HS- + OCl- --> S + Cl- + OH-

    HS- + 4 OCl- --> SO42- + 4Cl-

    Any elemental sulfur should be filtered out. The sulfur would be best filtered by a DE filter, although you might need to use an activated carbon filter to remove final suspended sulfur.

    Sulfates shouldn't cause any smell. Shock to about 10 ppm using liquid chlorine (sodium hypochlorite) and keep it there until all of the sulfide has been oxidized.

    Hydrogen peroxide can also be used to oxidize the sulfide to sulfur or sulfate if the chlorine does not work. Hydrogen peroxide is a chlorine reducer so you would have to use enough to reduce all of the chlorine and then add about 3 ppm hydrogen peroxide for every 1 ppm sulfide. pH needs to be raised to about 8.2 for this to be most effective.

    A properly designed, installed and operated ozone system can give very good water quality. However, a well designed system is expensive for the initial setup.


    Use of MPS (aka non-chlorine shock) to shock might help oxidize sulfides to either sulfur or to sulfate.

    Have you had the water tested for hydrogen sulfide? What are all of your other chemical readings?

    Free chlorine

    Combined chlorine


    Total alkalinity


    Cyanuric acid


  6. Ozone primarily reduces chlorine to chloride. There are two different reactions of ozone with hypochlorite ions.

    O3 + OCl- --> 2O2 + Cl-

    ozone + hypochlorite --> oxygen + chloride ion

    2 O3 + OCl- --> 2O2 + ClO3-

    ozone + hypochlorite --> oxygen + chlorate

    The first reaction accounts for 77 % of the reactions and the second reaction accounts for 23 % of the reactions.

  7. I don't think that there is a clearly superior product. There are many factors that go into the strength and durability of the structural shell.

    1) The experience and expertise of the builder.

    2) The thickness of the shell.

    3) The strength ratings of the concrete.

    4) The diameter and spacing of the rebar.

    5) The preparation of the ground.

    As for mixing application types, you don't want to do that. The shell should be shot in one continuous process to achieve a monolithic structure with no cold joints.

  8. As you can see in the picture, the valve is a pretty simple device. There is a main body and a cover plate. The cover plate slides up and down on a center pole. There is an O-ring at the top of the main body, which you can see in the picture. There is a spring on the center pole that helps keep the plate down.


    The valve is threaded into the main drain. When there is more water pressure under the valve than above it, then the valve will open to allow water to go from under the pool into the pool.

    Usually, if the valve gets pulled up by suction, it will fall back down and reseal. However, sometimes grit will cause it to not fully seal and there will be a leak. Sometimes it can reseal on its own.

    The valve can leak at the threads and it can leak if the O-ring becomes deteriorated. The diver probably should have replaced it while he was down there, especially if it is the original one.

    I usually try to keep minimum suction on main drains. Most of the time, I leave them turned off.

    The main drain cover needs to be replaced with a new cover and properly secured before anyone uses the pool. A loose, broken or missing cover is a serious safety hazard. The new cover needs to be compliant with the new safety standards.

  9. For heavily used spas, an ozonator will reduce oxidizer demand. For lightly used spas, an ozonator will tend to increase the amount of chlorine that needs to be added.

    This is because ozone oxidizes bather wastes, but it can also react with chlorine and convert it into chloride or chlorate.

    The silver won't have much of an effect either way on the amount of oxidizer demand.

  10. I think that as long as the minimum temperature is above 40 degrees F for 4 days before plastering, the day of plastering, and until the pool is full, then temperature shouldn't be a problem.

    During periods of daily rain, the local water table can get higher than normal, which can increase the risk of floating, or water weeping through the gunite while plastering. However, the water table can be controlled to prevent the possibility of the pool floating and to prevent the possibility of water weeping into the area between the plaster and the underlying concrete.

    You don't want to plaster on a windy or rainy day.

    Here are a few references you can review if you want further, more detailed information. The last reference link might not work, is primarily for commercial pools, and is really too much information, so you should probably skip that one.

    Reference 1

    Reference 2

    Reference 3

    Reference 4

    Reference 5

  11. I would suspect the hydrostatic relief valve. If the main drain gets covered, there can be enough suction to cause the hydrostat to open and it can get stuck due to debris. The valve can then reclose on its own.

    This time of year, there are more leaves, which might be covering the main drain. How much suction do you have on the main drain? Do you ever run the vacuum head directly over the main drain? That can also cause it to lift up and leak.


    Hydrostat in the open position.

    Do you know what your local water table is? If you dug a hole in your backyard, how deep could you go before hitting water?

    Another thing to consider is that if the water is heated and uncovered, then it will lose substantially more water due to evaporation when the air temperature is lower.

  12. My most recent post is my answer in my own words. I did not get the information from any other source. I only require three things that should be fairly easy to get.

    A swimming pool is a luxury. If someone does not have access to basic supplies, then perhaps a swimming pool should not be on the top of their priority list. If the person does not have even basic transportation, then why are they buying a pool? What happens when they need food or need to get to a doctor?

    If he can get a swimming pool, then he can get the things I suggest from the same place. I need certain tools to do my job properly. There is no need to compromise on that.

    I give exact amounts of chemicals to add based on the test results. That's as easy as it's going to get.

  13. Ok, I will attempt to write a better post for the OP.

    You will need the following.

    (1) Basic 3-way test kit that can do chlorine, pH and alkalinity.

    (1) 1-pound (454 grams) dichlor.

    (1) Gallon (3.8 liters) of regular, unscented 6 % bleach or 12 % liquid chlorine.

    Every night after all swimming, measure the chlorine and pH.

    If the pH is between 7.2 and 7.6, then add the following amount of either 6 % bleach or liquid chlorine:

    Chlorine reading............6 % bleach............ 12 % liquid chlorine

    .........0...........................8 oz. (240 ml)..............4 oz (120 ml)

    .........1...........................6 oz (180 ml)...............3 oz (90 ml)

    .........2..........................4 oz (120 ml)................2 oz (60 ml)

    .........3..........................2 oz (60 ml)..................1 oz (30 ml)

    If the pH is between 7.7 and 8.0, then add the following amount of dichlor:

    Chlorine reading..............dichlor

    ..........0.............................1.00 oz (28 grams)

    ..........1.............................0.75 oz (21 grams)

    ..........2.............................0.50 oz (14 grams)

    ..........3.............................0.25 oz (7 grams)

    Measure the alkalinity and post that when you get a chance. If the pH is below 7.2 or above 8.0 then post back for further instructions. If your chlorine is zero at the end of each day, then increase the amounts of chlorine to be added by 25 %. Use only a maximum cumulative total of 13 ounces (369 grams) of dichlor. After using a cumulative total of 369 grams of dichlor use only bleach or liquid chlorine.

  14. Like i said before, You would make a great politician. Never admit any wrong doing, and your way is the best, and only way.


    I will admit that my post was not perfect. I'm sure that I could have written a better post

    It should be a collaborative effort. I think that is evident in this case where there were solutions posted and debated ending up with a better answer than any one person would have come up with alone.

    In this thread, I admit that I could have done better and I encourage others, including you, to contribute.

    In addition, what do you have against politicians? The vast majority are honest, hardworking decent human beings who are doing their best to improve everyone's life to the best of their ability. Perhaps you should have a little more respect and appreciation for the people who work so hard to provide you with the infrastructure you need to live a free and happy life instead of complaining so much.

  15. You mean the existing level? I think it's safe to say there is none, since he came here asking what to put in.

    Then he would put 0 in the starting box and 4 in the end box in the pool calculator to determine how much chlorine to use. Either way, he measures the amount using the test kit and uses the pool calculator to determine the amount of dichlor or bleach to use. I'm not sure why this seems to confuse you so much.

    Unbelieveable, let me get this strait. If you had more time, you would have given him more than the 7 pages you initially gave him to look at?

    NO, it's not about amount; it's about clarity and specificity.

    And ALL your posts come across as a chemist, in a lab, with a internet connection, and no real practical experience in the pool industry.

    Probably more on the job time in all phases and all types of pools than you.

    The OP obviously has an interest in keeping his pool safe and sanitary; otherwise, he would not have posted in the first place. He has invested time and money acquiring and installing the pool. Is it really too much to expect that he learn a few basics of chemistry since that is going to make a huge difference in his and possibly his family's ability to enjoy it? Since he has only a short amount of time to enjoy the pool, any downtime due to nasty water would seriously diminish the value he hopes to get from it.

    As far as throwing it away in a month, perhaps he will and perhaps he won't. That might be the plan, but plans have a way of changing. Summer in Australia is December, January and February; so it's likely that the pool will be used for more than one month. Either way, I gave him a simple solution and I referred to more complete information should he wish to explore the subject further.

    For someone who's supposed to be a professional, you sure do seem to have a cavalier attitude about the users' health and safety. So far, you haven't contributed much to this thread other than to attempt to criticize my efforts to help the OP. As I said before, if you think that you can give worthwhile advice, then you should do so, or maybe not.

    i fell asleep during chemistry. Don't trust me with the water.

    You don't even know when your'e being clowned.

    Trust me; I know who the clown is.

  16. But you didn't tell him how much, thats all he really wanted to know .

    I did tell him how much to use. The amount to add depends on the chlorine level. I told him where to keep the levels and to use the pool calculator to determine how much to use.

    Look, this guy just wants to get in this thing and drink beer, do you really think he's going to stand there and try to remember all these cocktails you are prescribing?

    You're the only one referring to "cocktails". You don't know who will be using this pool. Perhaps children will be using it. It needs to be properly maintained to be safe and sanitary.

    My GOD! MORE detailed? You're messing with me, right?

    No, it could be made clearer by providing step-by-step directions.

    There was nothing wrong with any of my posts, and there was no run around. I do not need you apologizing for my posts.

    If you think that you can post better advice, then you should do so.

    Your advice to add "1 maybe 2 Fl. Oz of liquid Cl" really does not help very much. How often should he add this amount of chlorine? What about pH?

    So you tell him to pour over almost 7 pages of that, just to find out he needs about a mouthful of Cl???

    Why are you measuring chlorine in "mouthfuls"? What kind of nonsense is that? Is that how you measure chlorine? Is that how you tell your customers to measure chlorine? What is the conversion factor to fluid ounces or milliliters?

    Your post comes across as nothing more than a petty attack for no legitimate reason.

    Thank you, i needed to know how a forum works.

    You're welcome.

  17. At any rate, I think the point is moot since the OP has not posted back. I think he was scared away by too much unneeded info at once when he just asked a simple question of how much chlorine should he put in. If that were answered I believe he would have been more receptive to listening to advice on pitfalls to watch out for and the pros and cons of different types of chlorine.

    I did provide information about how much chlorine to add. There is no reason to believe that the OP was scared away. Perhaps the OP has not posted back because they have been given enough information and don't need any further assistance. They didn't have any trouble asking follow-up questions when they wanted more information.

  18. I referred him to the more complete chemistry information. However, I also gave him a simple answer:

    At a minimum, you need to maintain a consistent chlorine level of about 2 to 4 ppm and a pH between 7.2 and 7.9. You can use regular, unscented bleach for chlorine and muriatic acid to lower pH as needed.

    You can use the pool calculator to calculate the amounts of chemicals to add to change a chemical level.

    This way he can just use the simple answer to get started and achieve the minimum balance, and he can refer to the other information if he wants to. I told him where to keep the chlorine and pH, and I told him how to calculate how much chemicals to use.

    He could have used my "At a minimum" answer to take care of the pool using bleach without referring to the other material. The pool calculator showed how much bleach to use to achieve the recommended level of 2 to 4 ppm, and what to use to adjust the pH if necessary.

    I agree that dichlor would be a good solution. They could buy one pound of dichlor for about $ 5 to $ 7(1) (2) and would use about 13.5 ounces (weight).

    Assuming 2 ppm chlorine per day (0.45 ounces (weight) per day), that would raise the cyanuric acid to about 54 ppm after 30 days. If the poster decided to continue to use the pool after the thirty days*, then they could switch to regular, unscented bleach or liquid chlorine.

    I think that they could use bleach, dichlor or they could alternate between dichlor and bleach to help achieve a stable pH, using bleach when the pH was low and dichlor when it was high. A simple chlorine and pH test kit should be sufficient.

    I will admit that my post was not perfect. I'm sure that I could have written a better post if I had more time to write a detailed step-by-step guide providing exact instructions for testing and adding chemicals. I try to provide the best advice I can in a limited amount of time.

    I recognize that it is a "toy" pool that would only be used for a short period of time, that's why I gave the "At a minimum" answer. Even though this is a "toy", there are certain basics that need to be followed to ensure a safe and sanitary environment for those who will use the pool.

    Part of the way a forum works is by multiple people providing answers that work together that address errors or weakness in previous posts to hopefully end up with a solid solution. It should be a collaborative effort. I think that is evident in this case where there were solutions posted and debated ending up with a better answer than any one person would have come up with alone.


    *Although they say, "it's getting thrown out in a month", they also say that they want to use the pool for the "summer", which implies more than a month.

    Note: The poster says that the volume is 3.5 kiloliters, which is equal to 3.5 metric tons or 925 gallons (as waterbear noted).

  19. 1. Will water percolate through the gunite in cases where the plaster has become thin due to etching? Or is the gunite waterproof as well?

    2. Would a crack in the pool bottom typically be visible to the naked eye assuming very clear water?

    3. Is it much more likely that the leak is in the main drain piping or pool light enclosures?

    4. How far down can I let the water drain before running a significant risk of the pool trying to pop up out of the ground?

    1) Gunite is not waterproof. However, as long as there is not a lot of exposed gunite, there should not be much water loss. Even thin plaster should be fairly waterproof, so you shouldn't expect much loss through plaster.

    2) Cracks can be difficult to see if they are very thin.

    3) Leaks can be difficult to diagnose. There are many places that can leak. Plumbing, grout, cracks in the plaster, the light conduit, the hydrostat etc.

    4) It depends on the local water table. The leak should not drop below the water table, so it is somewhat self-limiting. You should not allow the water to drop below about 12 inches in the shallow end.

  20. Thats Ok, I'll just start ignoring your posts too, and come in behind you and say again what you just said. As you have done in the past.

    I did not ignore your post. As I said earlier, I hadn't seen your post until after I posted. And, I didn't say what you did. I posted what the manual said about what to check. The only thing that was in the manual checklist that you had said was about the fan not operating properly.

    Also, when I said, "This post did not include enough information to indicate any probable or likely cause", It looked like I was referring to your post, I meant the original poster. I quoted part of your post to support that. I did not mean to imply that your post was not helpful. I should have written more carefully.

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