Whether you’re just moved into a home that comes with a swimming pool or you can’t afford to pay the pool guys to service your pool anymore you can easily learn basic water chemistry to balance the swimming pool water yourself.
Testing and balancing the chemical components of your pool water is the first and most important part to your pool maintenance routine. Balanced and properly sanitized pool water guarantees a safe swimming environment for your family and friends. Chemically balanced water prevents the build-up of calcium scale and other deposits on the pool surfaces, equipment and inside pipes. Balanced pool water also prevents the pitting, etching, dissolving and staining of pool surfaces and tile grout.
Table of Contents
Testing Swimming Pool Water
Testing pool water is the most important component to your pool maintenance routine and the first step to balance your swimming pool water. The water should be tested twice a week in the summer to identify any minor issues before they become a problem.
If you own or are responsible for a pool you need a pool test kit or chemical test strips. I recommend the test strips as they are accurate and easy to use.
1. Pool Test Kits
The process is as follows:
- Take a water sample and place it the provided tube or vial.
- Add the prescribed number of drops of a chemical into the tube.
- Some kits require adding two chemicals to the tube.
- Put a lid on the tube & shake it up.
- Compare the color of the fluid to the test chart.
- Record your reading for free chlorine.
Now repeat the above test for pH, total alkalinity, stabilizer, calcium hardness, bromine and whatever else you need to test.
2. Pool Test Strips
The process is as follows:
- Take a test strip and dip it into the pool water for 5 seconds.
- Remove the strip and wait 10-20 seconds.
- Compare the colors on the strip to the label on the container.
- Record your readings
Most test strips test 4 or more tests at once.
The common swimming pool strips test:
Free Chlorine, pH, Total alkalinity & Stabilizer.
The common spa pool / hot tub strips test:
Free Bromine, pH, Total alkalinity & Calcium hardness.
There are other test strips available, such as:
Salinity, Phosphate, Baquacil, TDS
3. Take a Sample of Water to a Pool Shop
If you are lucky and there is a local pool shop nearby you can take a water sample to the pool shop for testing and advice on how to balance the swimming pool water. In recent times, many pool shops have closed, converted to mobile businesses or gone online.
Pool shops are very expensive and you can source everything online for less money. As a result, I haven’t been to a pool shop in years.
Advantages of Pool Shop Test
- The result will be accurate
Disadvantages of Pool Shop Test
- Takes too much time
- There may be a charge for a test
- The shop will try to sell you overpriced chemicals
- The shop will try to sell you other services
Pool Test Strips vs Pool Test Kits
I started out years ago with the old style pool test kit. These are still available and many people still use them but they have been superseded by test strips.
It takes time to work through each test and record the results and you do need to record the results because you need to empty the tube after each test to perform the next test. The tests are more prone to error because you may use the wrong indicator fluid and if you count the number of drops incorrectly you get an incorrect result.
However, rather than using a test kit I recommend pool test strips to determine how to balance your swimming pool water. They are far more convenient, simple to use and the result will be as accurate as a test kit. Also you really need to test your pool water twice a week so strips are more convenient.
Pool Test Strip Advantages
- Inexpensive to buy
- Very accurate if used correctly
- Easy to use
- Fast result (20 seconds maximum)
- Multiple results on the one test strip
- No need to record the test. You have a strip with the results.
- Specialized strips for outdoor pools, hot tubs, salinity, etc.
Pool Test Strip Disadvantages
- Strips have an expiry date but so do the chemicals in test kits.
- Touching the chemical pads will give an incorrect result.
Pool Maintenance Routine
The following table is a typical pool maintenance routine for the whole year. If you follow the routine you should have a trouble-free pool experience. When you detect a small issue early and fix it immediately you prevent it becoming a problem.
Daily Maintenance
- Check the water level
- Clear the skimmer basket
- Skim the pool surface with net
Weekly Maintenance
- Test pool water
- Vacuum the pool
Monthly Maintenance
- Backwash the filter
- Clean the filter cartridge
- Test – Salinity, Alkalinity, Calcium hardness, Metals, TDS
Yearly Maintenance
- Check Chlorinator cell
- Open pool
- Close pool
How to Balance Swimming Pool Water
To learn about all the pool chemicals and how to adjust them in your pool refer to our Pool Chemistry Course.
The following are the basic chemical indicators and desired levels for a backyard freshwater or saltwater pool. If your pool water is maintained within these parameters your pool will always be clear and safe for swimming.
pH Level 7.2 – 7.6
Free Chlorine 1.0 – 3.0 ppm
Cyanuric Acid (Pool Stabilizer) 30 – 80 ppm
Salinity 2700 – 4500 ppm
Total Alkalinity 80 – 120 ppm
Calcium Hardness 200 – 400 ppm
Total Dissolved Solids (TDS) 3000 – 6000 ppm
How long does it take to balance swimming pool water?
Usually you need to run the pump for one or two cycles to balance pool water. When your test result indicates that the pool water needs rebalancing it is recommended to add the required chemicals in two stages. In the first stage only add 75% of the required chemical and wait for the pump to circulate the water before retesting. This needs at least 4 to 6 hours depending on the volume of water in the pool. The test should indicate the water is much closer to the target level. Now add a small amount of chemical to bring the water to the desired target level. A common mistake many pool owners make is to add too much chemical and overdose their pool. Then they have to add a different chemical to bring the indicator back the other way.
How long can water sit in a pool without chlorine?
The answer to this question depends on the time of year. In the summer the pool water will become unsanitary faster than in the winter because the heat will use up the remaining chlorine quickly. Normally, water can remain in a pool for 3 days without treating the pool water before it becomes unsanitary. Airborne bacteria and algae spores will invade the pool begin growing and turn the water green.
What happens if you swim in a pool with too much chlorine?
The recommended level of chlorine is between 1 and 3 ppm.
Once the chlorine level becomes higher than the recommended upper level of 4 ppm the pool water would be unsafe for swimming. The water may cause red eyes, itchy skin, nose & throat irritation, rashes, coughing, asthma and general sickness.
When you shock your pool with a high dose of chlorine you need to run the pump for at least one cycle and retest the water to ensure the chlorine level is between 1 and 3 ppm before you allow anyone to swim in the pool.
Can you shock your pool with liquid chlorine?
Yes, sodium hypochlorite comes in liquid form and is the same as the granular form of pool shock. Most people prefer the granular form because it is safer to handle than a liquid but it doesn’t matter which one you use. Please ensure you practice safe handling of chemicals.
Read our article on How to Shock Treatment Your Swimming Pool
Which is better granular or liquid chlorine?
Personally, I prefer the granular chlorine because it is safer to handle. If you pour granular chlorine over yourself you cannot do much harm whereas pouring liquid chlorine would severely burn you. The real difference between the two is that granular chlorine and shock products are usually stabilized (contain cyanuric acid) whereas liquid chlorine is unstabilized (no cyanuric acid).
How long after adding salt to the Pool can you swim?
Salt is the least dangerous chemical you add to a pool. However, as with all other chemicals it is recommended to run the pump for at least one complete cycle to fully circulate the water and mix in the chemical before you swim in the pool. The best time to add salt is in the evening, run the pump overnight, and the pool is ready for swimming the next day.
How do I make my pool water crystal clear?
You may have correctly balanced your swimming pool water but it still doesn’t have that sparkling clean appearance. Sometimes tiny particles build up in pool water that takes the sparkle away. These particles are so fine that they never sink to the bottom but stay suspended in the water. Try adding clarifier to the water to remove the fine particles. The use of a clarifier chemical will help to combine these tiny particles together into larger particles that can be filtered out or fall to the bottom and can be vacuumed manually or by a robot cleaner.
I also recommend you add algaecide at the beginning of the season to provide protection against an algal bloom.
Over time, chloramines, metal ions and dissolved solids build up in pool water and cannot be filtered out. Pool surfaces become rough and coated with calcium scale that needs to be cleaned away. The only way to solve these issues is to empty the pool, clean the surfaces and refill it. I recommend pool water should be changed every 5 or 6 years to solve these problems . Once you refill the pool you can easily balance the swimming pool water again.
What time of day should I shock my pool?
The optimal time of day to shock a pool is after your family and friends have finished using the pool for the day. Shock the pool in the evening when the chlorine shock will not be affected by UV light and heat. Adding shock in the middle of the day in the hot summer will be far less effective as the sun will burn it off quickly. Run the pool pump overnight to circulate the water mixing the shock into the pool. The next morning your pool is ready again for action.
What makes pool water look blue?
A swimming pool with a white plaster lining or any other type of surface will look light blue when filled with water. Light is a mixture of varying wavelengths of electromagnetic energy that we can see with our eyes as colors. Think of a rainbow or when light passes through a prism and the colors are separate. When all the colors mix together the light is clear and natural. Water absorbs the red, indigo spectrum of light and reflects the blue, violet end of the spectrum making the pool water look blue.
How do you keep a pool clean without chlorine?
Salt water chlorination
Salt water chlorination is the most popular alternative to having a fresh water pool and adding chlorine. A saltwater pool has salt dissolved in the water that is electrically split into chlorine by a salt water chlorinator unit. Every time the pump operates it draws salt water from the pool, filters it, passes the clean water through the chlorinator to produce chlorine and pumps the water back to the pool. Effectively, a salt water pool is a chlorinated pool with the same amount of free chlorine in the water as a chlorinated fresh water pool. The level of salinity is very low and similar to the salinity of tears in the human eye. The water is nowhere near as salty as seawater so it’s very safe for people to swim in.
Read our post on How to Convert Your Pool to Salt Water
Ozone water purification
Ozone water purification is an alternative to chlorine. The pool water is sanitized by pumping it through an ozone treatment unit that purifies and cleans the water before returning it to the pool. The water in the pool itself is not treated with a chemical so the pool water must be frequently pumped through the ozone unit to treat the water. Usually ozone treatment is more expensive than chlorination treatment.
Bromine
Bromine can be used to sanitize a swimming pool. However, bromine cannot be stabilized with cyanuric acid like chlorine so it’s less useful in an outdoor pool as the UV light will render it ineffective. I recommend to use bromine in hot tubs and spa pools because of the higher temperature, small volume of water and less reactivity to your skin. The other disadvantage of bromine is that it costs much more than chlorine. As a result pool owners prefer to use chlorine in a swimming pool and use bromine in the spa or hot tub. Bromine can be used in an indoor swimming pool because there is no sunlight or UV radiation to inactivate the bromine.
Biguanide
Biguanide (polyhexamethylene biguanide) is a chlorine-free and bromine-free alternative sanitizing product that can be used in swimming pools. This chemical works by combining with contaminants in the water to produce insoluble particles that are trapped by the filter. Biguanide has many advantages over chlorine especially being gentler on skin, hair and eyes and is chemically stable in water even with UV light, however, the main disadvantage is that it’s more expensive than chlorine and less effective requiring a higher concentration than chlorine to sanitize water.
Please read our post on Biguanide Pool Chemical System
Conclusion
Some people believe owning a pool is a lot of work with continuous maintenance.
That’s simply not true.
Once you have owned or operated a pool for a few months, knowing how to test and balance swimming pool water becomes very easy and natural. Once the water chemistry is balanced and the filtration equipment is set to optimal performance most pools never need much maintenance at all.