Swimming Pool Guides & Reviews by Certified Pool & Spa Operator®
Pool Chemistry: The Basics
Pool Chemistry 101
Sanitation and water balance are the two most important things concerning pool chemistry.
Due to the delicacy of pool water, you must balance it to achieve the right harmony. Water balance means you maintain a pH level of anywhere from 7.4 to 7.6 in the water. This is a little bit higher than neutral when looking at the pH scale.
The three ingredients which balance water are calcium hardness, pH, and alkalinity.
Keep the pH level at a minimum of 7.4 and maximum of 7.6. There are so many outside elements which can influence the pH level of the pool water, such as rain and the people who swim in it. If you have low pH, then you have acidic pool water. If you have a high pH level, you have basic water.
If you swim in low pH water, your eyes would likely burn. If you have high pH water, your eyes would likely dry out.
The way you balance the pH levels in pool water is with chemicals called pH increasers and pH decreasers. If you have high pH levels, then you would use a pH decreaser in your water. If you have low pH levels, then you would use a pH increaser. Make sense?
The level of alkalinity should be between 100 ppm and 150 ppm. The abbreviation means “parts per million.”
Alkalinity assists in maintaining the pH levels and preventing them from increasing or decreasing. It does this by absorbing any huge water changes which influence the pH levels. This is known as a pH buffer.
Keep some alkalinity increaser readily available to use when needed.
If you own a plaster pool, the level of calcium hardness should be within 200 ppm and 275 ppm. Even though calcium hardness does not really relate to water balance, it must be discussed because water seeks calcium wherever it can get it. If it has low amounts of calcium, the water may feed on the plaster of your pool to get it.
When your water has more calcium hardness added to it, the equipment and walls of the pool stay better protected. But don’t add a lot of calcium because you may experience issues like scaling in the pool. Just add the calcium hardness once at the start of the season. Then monitor the level of calcium hardness throughout the season. If you end up having too much calcium in the water, drain the pool water a little bit and then add some fresh water.
Maintain Balanced Water
If you’re new to maintaining pool water, then test the levels of alkalinity and pH every day. There are test strips available in stores. Use these strips to test the water for these elements to see if the water is balanced. If the results show balanced water, then you should keep some pH increaser, pH reducer, and alkalinity increaser stored away for the future.
There are no alkalinity decreasers sold in stores. Whenever you have low alkalinity and pH, you only need to add an alkalinity increaser to boost both of these chemical levels in the water. If you still don’t have a 7.4 pH level after doing this, then add some pH increaser until you do. And if you notice that you have high levels of alkalinity and pH, then you can lower both levels with just the pH decreaser.
If the pH is low and the alkalinity is high, add some of the pH decreaser in the water to lower the alkalinity. Obviously, the pH levels will be lowered by this too. Just worry about getting the alkalinity to the proper level. After you do this, you can use a pH increaser to raise the pH level. This procedure may be difficult at first, so keep practicing until you get the hang of it.
You’ll want a consistently balanced pool because it helps the sanitizer do its job better.
Chlorine is the most popular sanitizer used for pools. If you don’t want to use chlorine, other types of sanitizers include bromine, biguanide, and minerals like copper and silver.
If you use chlorine, its level should be 3 ppm.
Chlorine is an effective and affordable way to kill algae and bacteria in the water. You can add chlorine to your pool water by using chlorine tablets, a salt chlorine generator, powdered chlorine, or chlorine granular. The salt chlorine generator can make chlorine from table salt.
Most people like to use chlorine tablets because they’re the easiest to apply to the water. You can purchase 1-inch or 3-inch tablets. Just add them to your pool’s skimmer basket, floating chlorine dispenser, or chlorinator.
Make sure the active ingredient of your chlorine product is either Dichloro or Trichloro. Since these are stabilized chlorine products, the sun’s UV rays won’t be able to diminish the chlorine as fast as it can when the chlorine is not stabilized. You’ll learn more about this later.
The level of bromine in your water needs to be between 3 ppm and 5 ppm. Since it doesn’t have a chlorine smell, bromine is recommended for indoor swimming pools and hot tubs.
Bromine doesn’t eliminate algae as well as chlorine. Don’t use bromine on outdoor pools which have the sun shining down on them. Bromine will be destroyed by the sun quickly since it is not stabilized.
The level of biguanide should be between 30 ppm and 50 ppm.
Biguanide is a good alternative to chlorine because it sanitizes pool water quite effectively. There will even be a newfound smoothness to the water too after you apply this chemical.
SoftSwim and Baquacil are just some of the sanitizers which shouldn’t be added in with regular pool chemicals. If you choose one of these sanitizer brands, then you must use their pool chemicals too, such as their algaecides and shocks. The chemical packages of these brands cost more than standard chlorine chemicals.
The chlorine level should be 0.5 ppm.
A mineral system introduces minerals like copper and silver to the pool water. Their function is to sanitize the water. However, it takes these minerals longer to clean the water than chlorine. Even so, you cannot replace chlorine with a mineral system. You must still use chlorine in conjunction with the mineral system. You don’t need to use much chlorine, but some may be necessary.
Pool shocking means you’re putting chlorine in your swimming pool to kill the organic materials in the water, especially the bacteria. When a chlorine particle goes after bacteria like this, it is called combined chlorine. The chlorine particles eventually break apart in the water after they’re oxidized. You can oxidize the chlorine by adding potassium monopersulfate or extra amounts of chlorine. This will cause it to achieve breakpoint oxidation.
The best pool shock for this is calcium hypochlorite. Use this at least one time per week in your pool water.
You must have 10 ppm more chlorine than combined chlorine to achieve breakpoint oxidation.
There are two possible readings for chlorine. There is combined chlorine and free chlorine. When you have combined chlorine, it means the particles have killed bacteria already. When you have free chlorine, this is chlorine which is readily available to kill but hasn’t killed yet.
There is typically unstable chlorine in most pool shock products. As a result, the UV rays of the sun will destroy the cleaning formula quickly after it’s done its job. For this reason, wait until nighttime to shock your pool with these products. Keep the pool running for at least 8 hours during the course of the night.
Your pool should be oxidized or shocked at a minimum of once each week.
Other Pool Chemicals to Consider
You can maintain a clean and sanitary pool if you use sanitizer, calcium, pH, and alkalinity. But there are other pool chemical options available too which may interest you.
Stabilized chlorine is what you usually add to pool water. But if you’re beginning with fresh water, then you need a water stabilizer like cyanuric acid to start with. This will ensure the UV rays of the sun don’t burn the chlorine away quickly. Cyanuric acid basically shields the chlorine from the UV rays.
Algaecide prevents algae. Some of these products are supposed to kill algae too, but it is better to use chlorine for your algae killing needs. Algaecide can be your backup whenever your water is low on chlorine. The algae can be contained with the algaecide while you work to increase the chlorine levels again.
Don’t use algaecide if your pool has too many algae. There are better solutions available for killing large amounts of algae in a swimming pool. They will also prevent them from returning.
When your pool gets cloudy from lots of tiny particles, a water clarifier works to combine those small particles into big particles. That way, the filter can block them better as they pass through it.
A flocculant, or floc, will also combine those tiny particles. However, the particles then sink to the floor of the pool. You need to manually vacuum the floor to remove the particles.
If your water has iron, copper, and other metals, a metal remover can assist your filter in filtering them. This is also called a stain and scale remover too. If you don’t remove these metals, they can end up staining your pool’s walls.
To summarize, your pool chemicals need to be at these levels for your swimming pool to stay safe:
– pH should be within 7.4 and 7.6
– Alkalinity should be between 100 ppm and 150 ppm
– Calcium hardness should be within 175 ppm and 225 ppm. If you have a plaster pool, it should be between 225 ppm and 275 ppm.
– Salt water pools and chlorine pools need between 1 ppm and 3 ppm.
– Bromine pools need between 3 ppm and 5 ppm.
– Biguanide pools need between 30 ppm and 50 ppm.
– Mineral system pools need the chlorine to be 0.5 ppm.
The water filtration and circulation of your pool must be consistent. Skim and vacuum your pool regularly too.
If you can remember to add chemicals, circulate the water, and clean the water, then you’re all set.