Basic Pool Chemistry


Owning a pool is fun. It provides hours and hours of relaxation but also is a place where during summer you could organize gatherings with grill, beer, or kids running around, playing pool games and stuff like that. But, it also has that other side, because every pool requires a heavy portion of maintenance.

That side, although not so beautiful and fun at the first sight, is equally important for our pool’s and our own health, because taking care of chemicals, water balance, sanitation, and cleaning filters is a necessity to organize those barbeques and fun gatherings without risking our own health.

Why Is An Keeping Eye On The Chemistry In Your Pool Important?

Before you get into your pool or call up your friends to join you for a cold beer in warm water on the hot summer day, you must make sure your pool is not just clean, but it also has well pH-balanced value. This will not only help you keep your pool clean, but it will also affect the quality of water and make your time in the pool more enjoyable, keep your water sparkly and protect your guest’s health.

What Elements Affect Pool Chemistry?

As a pool owner, you’ll have to take care of two elements to keep your pool healthy and in a good shape. Those two elements are water balance and sanitation. Water balance refers to maintaining the pH level of the pool water in normal levels (from 7.4-7.6), a bit above neutral on the pH scale. And there are a few things you’ll have to look after to keep them within those boundaries – alkalinity, pH, calcium hardness.

Alkalinity is a so-called buffer for the pH level. Its purpose is to keep the water still and prevent pH levels from drastically changing. pH levels could vary as they are affected by lots of factors, like rain or temperature change. In other words, if the pH level drops your pool water becomes acidic, and if it goes up, water is essential.

For better understanding, the water we use daily for showering, washing, etc. is neutral. If it is not, it will cause your skin to dry out and will burn, so it is important to follow the quality of your water, and if it changes from the normal value to intervene and keep your pool’s pH level under control. Calcium Hardness is a sign your water needs calcium. If you leave it unattended, it could harm your pool.

Keeping Pool Water Balanced

OK, so, now when we know why is important to take care of your pool chemistry, we will explain how you should do it. It is not as hard as it sounds, and if you look at it from a scientific angle, it could be really fun.

When you run the first tests, the picture will become clearer. If the tests show you that the pH level has dropped drastically, you’ll need a pH increase to increase the pH level. On the other hand, if the pH level is above the upper limit, or the level of your alkalinity has changed, you’ll need a pH reducer. Also, the pH level could be increased with the alkalinity increaser.

If it goes slower than you’ve hoped for at the beginning, don’t worry. It could be tricky at first, but once you get to “know” your pool, you’ll find the right measurements and what is best for it, and how to properly use needed chemicals.


Another important part of keeping your pool healthy is sanitation. The most used thing for cleaning the pool is chlorine, but it is not the only option, as there are many other chemicals you could use for cleaning.

Chlorine acts as a bacteria and algae killer. The other plus and the main reason because it is so widely used is the fact that it is one of the least expensive ways to sanitize your pool. It comes in a few different shapes. The most traditional one is chlorine tablets – you simply place them on your pool chlorinator. The other options are salt chlorine generator, which turns table salt into pool-cleaning chlorine, and powdered chlorine. The powdered chlorine should be scattered in your pool, following the instructions.

Also, when you buy chlorine, pay attention, and look for the one that contains Dichloride or Trichloro. It means your chlorine has been stabilized, and that the sun rays won’t “eat it up” as fast as they would unstabilized one.

Other Options

As mentioned before, there are some other options, besides chlorine, you could use in cleaning your pool. Here you’ll find out more about them.

– Bromine is mostly used in hot tubs and indoor pools because it doesn’t smell bad. But, the negative thing is the fact bromine is not resistant to sunlight, and it eats it quickly. Also, it is not so good at protecting the pool from a certain type of algae that are found in the outdoor pools, so they get dirty faster.

– Minerals require a mineral system but are a quite efficient way of sanitizing pool water. If you decide to go with the crystals, add about 0.5 ppm. Minerals won’t act as fast as chlorine, but if you don’t want to use chlorine, they are a good option.

– Biguanide is probably the best alternative to chlorine. One big plus in choosing biguanide over chlorine is the fact that biguanide not only sanitizes your pool but also makes your water feel smoother and more enjoyable. It is a bit more expensive and it comes in liquid form.

– Shocking the pool is mostly used when you want to get rid of the bugs. It is the procedure where you add a big amount of chlorine to your pool to reach the “breaking point”. To maintain your pool’s sanitation, you’ll need to do it once a week, and by night.

– Breakpoint oxidation is done when the chlorine reading is above 10 ppm. When reading the chlorine values, there are two possible readings. One is FC (Free Chlorine), which represents the chlorine available to kill, and the other is Combined Chlorine (CC), the one that already is free of algae and grime.

You should know that these products contain unstabilized chlorine, so as mentioned before because the sun will eat the unstabilized chlorine exposed to the sun’s rays you’ll have to start it by night and leave your pool running until the sun starts to rise.

A Few Other Chemicals You Could Use

Although those basic items described above are more than enough to keep your pool clean and sanitized, some other options could help you and make your work easier.

– Algaecide is a chemical whose main purpose is to stop algae from spreading. The algae could attract bugs and dirty your pool, so you should try and prevent them. Although not as good as chlorine for destroying the algae, the algaecide won’t kill them but will stop them from spreading until you get the chlorine.

– Water Stabilizer is a good addon if you must use some product that contains unstabilized chlorine. The other name of the water stabilizer is “cyanuric acid”, and it decreases the rate of the sun’s chlorine eating, so the unstabilized chlorine will last longer in your pool.

– Water Clarifier is a product that will remove those big particles that make your water cloudy. With a water clarifier, you’ll remove them from your water quickly.

And if there are some kinds of metals in your pool, like copper or iron, the metal remover will make the metal stains and particles visible, so your filter could easily remove them from your pool.

Calcium Hardness

Calcium hardness is the sum of all calcium dissolved in water. If the calcium level is high and the pH level makes it even more unstable, your water could become cloudy, or you could get scale. Also, calcium doesn’t behave well in hot water, so when the pool temperature rises, it could cause calcium to go wrong. The best calcium range is between 100 and 400 ppm and it is largely dependent on water temperature. If the calcium level gets low, you could add a hardness increaser and it will easily solve the problem. But, unlike pH or alkalinity, if the calcium level gets high and produces calcium hardness, the process is a bit more complicated.

The only way to solve it is to dilute your pool water with the one with the lesser hardness. It happens over time because of evaporation, temperature changes, and lots of other factors, so it is recommended to dilute your pool regularly to control it. Another way to reduce calcium hardness is to add a sequestering agent, which will chemically bond calcium to other minerals and prevent it from creating cloud water, but at the same time, it will stop the corrosion. But the best thing you could do if you face a calcium hardness problem is to call up a professional and ask them for an opinion.

How Long Should You Wait Before Using A Pool Again

You’re going through all of this with one goal – to get back to the swimming pool as fast as possible. So you probably wonder how much do you have to wait before you jump into the pool again? The answer is – probably an hour.

Most chemicals we use to balance pH, alkalinity, or calcium hardness will do their work in about an hour, so when an hour passes it is safe to go back and swim. This rule has an exception. When you shock your pool it usually takes about eight hours for the process to finish, so it is recommended to wait the next morning before you start using your pool again. But the safest thing to do is to wait 24 hours, as the chemicals will dissolve by then and do their job, the process will be done and the water will be good.

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Having a pool is a big responsibility because you need to constantly check on the chemicals, follow the possible changes, and react to keep your pool In healthy shape. It can be complicated, and maybe it sounds like something you couldn’t do, but if you follow these guidelines, all of these problems with pH, alkalinity, or calcium hardness can be solved in a no-time.

So, if you conclude that you have some of these problems, don’t panic or be lazy and wait to face them. Just remember, as soon as you finish with the balancing of your pool, you’ll get back to doing those things you love with the people you love. Relax in your pool with the burger and the beer and enjoy watching them having fun while floating with the drink in your hand, knowing they’re doing it in a safe and healthy environment. You’ve earned it.

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My name is David Hamburg. I am an avid water sports fan who enjoys paddle boarding, surfing, scuba diving, and kite surfing. Anything with a board or chance I can get in the water I love! I am such a big fan I decided to start this website to review all my favorite products and some others. Hope you enjoy!