Pool School 104 Total Alkalinity

Total Alkalinity Increaser 25lb Bucket

In Pool School 103 I talked about pH and how people get confused with the terminology when we refer to the pH being either Acidic or Alkaline, so Pool School 104 is where we are going to clear up that confusion and explain why this mineral level in the pool is important.

When we are talking about Alkalinity we are really talking about Total Alkalinity, which is a measure of all the alkaline minerals, dissolved into the pool water. Remember when the pH is above 7.0 the pH is considered alkaline, but here we are talking about alkaline minerals dissolved into the pool water not pH (the amount of hydrogen in the water).

The question often posed to us is; Why is Total Alkalinity important? There are actually two mineral balances that are important to your pool water and water in general; they are Total Alkalinity and Total Calcium Hardness. In this class I am just going to talk about Total Alkalinity and I will address Total Calcium Hardness in Pool School 105.

You will want to remember this for this class and for the next class; water wants a certain water balance, if it does not have that balance then it will go looking for it in whatever vessel it is being contained in. So in our case it is the surface of the pool that will be in jeopardy if the water is “out of balance.” Vinyl and painted surfaces will be the most often affected if your Total Alkalinity is not properly maintained.

What is the correct level for your pool? There isn’t actually one level that you would maintain but a range, we like 100 ppm to 150 ppm. This range gives you a good buffer. Some sanitizing systems require a different range usually 80 ppm to 100 ppm. People who use Ionizers (we talked about in Pool School 102) would maintain this level in the pool. There are some areas of Hampton Roads where getting the Total Alkalinity down below 150 is almost impossible because their make up water is very high in Total Alkalinity, for these customers we usually will allow up to 200 ppm but we have to balance that with the Total Calcium Hardness so we don’t end up with other problems in the pool.

What happens if the Total Alkalinity is below 100 ppm? The lower the Total Alkalinity the more difficult it will be to maintain a steady pH level. Total Alkalinity actually acts as a buffer to the pH, like a shock absorber so you don’t get big swings of the pH when you are trying to adjust it. In addition, you can actually get the Total Alkalinity down to zero (0) where there are no alkaline minerals in the water. This is a condition you really don’t want because the water is going to begin removing minerals from the surface of the pool and in a vinyl liner pool you will begin to see wrinkles form as the liner begins to relax and stretch. The wrinkles can only be removed by replacing the liner.

What happens if the Total Alkalinity is above 200 ppm? When the Total Alkalinity is too high it will have the opposite effect on the pH from a too low situation. So it creates a pH lock where you cannot get the pH level to move no matter how much pH lower or pH rise you add. It may also, if the pH gets too high, create an environment where scale is likely to form anywhere and everywhere on the pool surface, plumbing and equipment. When scale forms it is very difficult to remove from the pool surface, note I said difficult I did not say impossible. It takes weeks for the chemicals that remove scale from the pool surface to do their job, so prevention is your best protection.

Total Alkalinity is not a balance that changes day to day like Chlorine and pH, Total Alkalinity is a more long-range balance. What causes Total Alkalinity to change? Total Alkalinity has to be affected in order for it to change. The most common thing to affect Total Alkalinity is rain; rainwater is distilled water that has no minerals. So if you get a lot of rain your Total Alkalinity will be decreased the more rain the more the Total Alkalinity will be affected. If we get a hurricane with 20” of rainwater you can pretty much plan on having to adjust your Total Alkalinity. The other thing that affects Total Alkalinity is stabilized chlorine tablets and muriatic acid. Stabilized chlorine tablets have a pH level of about 2, so when they are dissolved into the pool water they drag down the pH level and the Total Alkalinity. At least once a week it is important that you check not only the chlorine level in your pool but also the pH level. You will usually find that the pH level will have dropped and will have to be adjusted up to keep the pH from falling below 7.0. If you let the pH level drop below 7.0 the water has gone from alkaline to acidic, once the water is on the acidic side it will begin to dissolve all the alkaline minerals from the pool water slowly dragging down the Total Alkalinity. If you let this go on for weeks on end you will end up with zero (0) Total Alkalinity, a very bad place to be. The other thing that affects Total Alkalinity is muriatic acid, we use muriatic acid to lower the Total Alkalinity when the level is 200 ppm or higher. There is a specific process we use to lower Total Alkalinity when using muriatic acid. When you have the water tested here and we determine that it needs to be decreased we will give you specific instructions on how this is to be done.

Some important things to remember; the Total Alkalinity does not change everyday and really only needs to be checked and adjusted every two to three months. If you are using stabilized chorine tablets keeping the pH above 7.0 is very important and should be checked and adjusted weekly. If you are busy and really don’t have time to keep close track of the pH we have a product that will help keep the pH in check called Balancer Tabs. When you add your chlorine tablets to your chlorine feeder you put one Balancer Tablet in the skimmer for every chlorine tablet you put in your chlorine feeder. NEVER put the Balancer Tablets in the chlorine feeder or the chlorine tablets in the skimmer with Balancer Tablets. Using Balancer Tablets will make it less likely the pH and Total Alkalinity will go way out of whack, but they do not eliminate the need to test the pool water at home or at our test lab, they just help keep the water balance from going too far out of whack.

Now that you have a better understanding of Total Alkalinity in Pool School 105 we will be talking about Total Calcium Hardness and your pool water, don’t be late for class!

Jim Garrison
The Guru of Pools at
Aegean Pools.

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16 thoughts on “Pool School 104 Total Alkalinity

  1. My Total Alkalinity is zero, but the pH is 7.2 so I’m confused that the pH is fine but still I have a zero total Alkalinity? Don’t put anything into the pool other than the pills in the chlorinator. What is causing the problem? Currently have emptied a quarter of the pool water to put fresh water in as the only thing I can attribute the problem to, is allowing rain to refill the pool???? Any advise would be appreciated.

    • Hi sendodth,

      You have a very interesting situation. Your problem has been created by either you source water or your chlorine tablets or both. As you will recall in Pool School 104 Total Alkalinity, “The other thing that affects Total Alkalinity is stabilized chlorine tablets and muriatic acid. Stabilized chlorine tablets have a pH level of about 2, so when they are dissolved into the pool water they drag down the pH level and the Total Alkalinity. At least once a week it is important that you check not only the chlorine level in your pool but also the pH level. You will usually find that the pH level will have dropped and will have to be adjusted up to keep the pH from falling below 7.0. If you let the pH level drop below 7.0 the water has gone from alkaline to acidic, once the water is on the acidic side it will begin to dissolve all the alkaline minerals from the pool water slowly dragging down the Total Alkalinity. If you let this go on for weeks on end you will end up with zero (0) Total Alkalinity, a very bad place to be.” This said we need to bring your Total Alkalinity back to the 100 to 150ppm range. However you have to do that very slowly, if you don’t your pool will be very cloudy for a long period of time from the chemical shock that will occur. I cannot give you an exact dosage of Sodium Bicarbonate to use without knowing how many gallons are in your pool. If you are in our area please bring a water sample to Aegean Pools so we can help correct your problem before it damages your pool surface. If you are out of our area please take a sample to a professional pool store in your area. The one thing I will mention is that when you bring up your Total Alkalinity you don’t want to add more that 10 lbs per 10,000 gallons of pool water per day. So if it called for 50 lbs of Sodium Bicarbonate and you have 20,000 gallons of pool water you would only add 20 lbs per day and that would require a treatment over three days. When you add it you would broadcast it widely, don’t concentrate it in one area. As a preventive measure make sure you have your pool water professionally analyzed at least three times a pool season at Aegean Pools or if you are out of our area at a professional pool store. If you have more questions let me know or come on by our retail store!

      Jim Garrison
      The Guru of Pools at
      Aegean Pools

      • Thank you for such a quick response. Unfortunately I am not in your area or I would be there in a second. I took the water to an area pool supply store where they tested it after complaints of itching by those using the pool and a home test showing bad results.

        The store advised that I should empty my 14,000 gallon fiber glass in ground pool which I refused to do. They indicated this was the best way to address the problem as adding chemicals would through the other results off. Since the only thing I’ve added to the pool is the chlorine tablets in the chlorinator I’m assuming that is the cause, that and the fact I’ve added more pills than was recommended. The only other thing is allowing the rain water to fill the pool when it rains.

        I did remove 1/4 of the water yesterday and then refilled with fresh water and turned off the chlorinator. I don’t think that by itself will solve the problem so I am thinking that given that my reading is currently zero, I should add 10lbs of the sodium bicarbonate to the pool and then get the water tested again next week. Will that work?

  2. So let me start from the beginning now that I realize how badly I’ve messed this up. First I have a 14,000 gallon fiberglass in ground pool. The test results on the water done by Leslie’s Pools, not in your area or I’d be in your shop, revealed a total alkalinity of zero. However my pH is 7.2 and listed as o.k. I started to add soda ash thinking it was sodium bicarbonate, not realizing it is actually sodium carbonate. Of course after adding the first 10lbs of soda ash, I kept doing more reading and discovered the difference. So I’ve stopped and will wait for hours and then have the water retested as I now fear that my pH will go through the roof while the impact on the alkalinity may not be significant. Any words of wisdom for a guy learning the hard way….

    • Alkalinity does change day to day I havr the opposite problem in my area Alk at 50 anf drops daily. Ph always on the rise and alk always dropping. Ho

      • Hi Joseph,

        Alkalinity could change day to day if you are having an issue with your pool. However, if you raise your total alkalinity to 150 ppm and your pool is leak free your total alkalinity will not change dramatically on a daily basis.

        Your fill water being 50ppm of total alkalinity will dilute your total alkalinity every time you fill your pool with it. If you are filing your pool daily, and in normal situations you shouldn’t have to, then you more than likely have a leak in the pool. If you fix the leak you will stop you alkalinity from dropping dramatically on a daily basis.

        In addition, in the article you will note, that if you are using stabilized chlorine tablets the pH of the table will actually lower the total alkalinity as it is dissolved into the pool water. However, if you bring your total alkalinity up to 150ppm it will give you a buffer and take at least 60 to 90 days before you would have to make an adjustment on average.

        The other thing that can affect total alkalinity is rain water. Rain water is distilled water and has no alkaline minerals, so if you get a lot of rain in your area that can have an effect on total alkalinity.

        In normal situations total alkalinity does not change dramatically in the short term.

        I hope this helps you understand what may be going on. Best of luck and enjoy your pool!

        Jim Garrison
        The Guru of Pools at
        Aegean Pools

  3. Thanks so much for this info we have had lots of rain in Washington tunderstorms this information is helpful to get my pool where it needs to be

  4. I run a 138,000 gallon competition pool at a college. I’m struggling to keep TA in range, 80-120. I check it weekly and average 50 ppm. I had it up to 70 by adding bicarb but it’s always dropping. 60 the next week then 50 and even as low as 40. Why is this happening? Cl 2.4, pH 7.5, CH 350, temp 84, TDS 1500. Using liquid chlorine 12.5% and muriatic acid.

    • Hi Obe,

      In reviewing your post, I believe your problem is the muriatic acid. Assuming you are injecting the acid into the plumbing, and not hand feeding, as the acid is injected into the pipe it is lowering the pH and the Total Alkalinity. There is no way around this issue other than constantly adding sodium bicarbonate (Alkalinity Increaser) to the pool water on a routine basis as needed. Because you are injecting sodium hypochlorite into the pool water this will cause the pH to increase, you have to lower the pH in order for the Chlorine to be effective. The only other option would be to use an automation system and a CO2 system to adjust the pH. With this system you will have the opposite issue, you will have to lower the total alkalinity over time. Either way you will have to make an adjustment.

      Best of luck.

      Jim Garrison
      The Guru of Pools

  5. Hello, I am struggling with a cloudy but blue pool. I have a 10000 gallon pool that has a ph of 7.8 and an alkalinity level of 40. My pool also isnt holding chlorine. Thank you in advance.

    • Hi Abby,
      Based on your brief summation of your problem, I would hazard a guess you have several problems. First, your pH is 7.8, that can cause cloudy water. So adjust that to between 7.4 & 7.6. Your low total alkalinity is not causing your cloudy water, but you will have difficulty keeping your pH in the proper range with a low total alkalinity. But, before you adjust your total alkalinity focus on your cloudy water. Your next best step would be to have your pool water professionally analyzed. You indicate you cannot maintain chlorine in the pool; there are several things that can cause that problem and a professional analysis will help narrow the field. If you get the water properly balanced and eliminate all the potential issues and the water is still cloudy and not showing any signs of clearing you have a filtration problem. Depending on the type of filter you have it could be the filter itself or, if you have a multiport valve it could be that.

      So to sum up fix whatever water chemistry issues you might have after having the pool water professionally analyzed(if you live nearby bring a sample to our water test lab), and if the pool is not clearing up focus on potential filter issues. Good Luck!

  6. Here’s one for you I’ve never before experienced as a pool professional: I’m servicing weekly a 30k gal bromine pool. The ph is consistent 7.4- 7.6, adding a pound or two of soda ash weekly. BUT the alkalinity drops 20-30 ppm per week! The pool is crystal clear and all the other numbers are in line. Can’t figure it. – Your Pool Boy, Ohio

    • Hi Curtis,

      The reason the Total Alkalinity keeps slipping down on you is the that the pH of a bromine tablet is 6.8. As the bromine tablets dissolve into the pool water the low pH will slowly drag down the Total Alkalinity. The more bromine (surface area of the bromine exposed to the pool water) the more it will affect the Total Alkalinity. There really isn’t anything you can do except adjust the Total Alkalinity as needed. As a side note, chlorine tablets have a pH level of about 2.0 and have an ever larger effect on the Total Alkalinity.

      Jim Garrison
      The Guru of Pools at
      Aegean Pools

      • Thank you. I suspected the bromine tablets. But none of my trichlor pools or other bromine pools have alkalinity bounce so sever? I even had the owner change bromine distributors. The only other thing I can think of is that the brominator is dispensing all the bromine to quickly (due to a faulty valve causing a shock efffect). When I get there a week later the brominator is empty and the brom is less than 1 ppm. What do you think? BTW there is no tree debris in the pool.

      • Hi Curtis,
        The reason you are seeing more of an effect is that there is way more surface area on eighty 1″ tables than you have on six 3″ tablets. Plus, if this is an outdoor pool, you will have to have a higher flow rate to keep up with the burn off from the sun. Hence, you will have more of an effect on the pH and alkalinity.

        Best of luck,
        Jim Garrison
        The Guru of Pools at
        Aegean Pools

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