What Hot Tub Chemicals Do I Need? The Complete Guide To Spa Chemistry 101

Do you really need chemicals for a hot tub? Yes, you need hot tub chemicals to maintain your hot tubs. Regular water care is necessary to ensure a relaxing moment in your clean hot tub. So, as a spa owner, you need to have an idea of the chemical required for the treatment and maintenance of your hot tubs.

You also need to know how, when, and why you should put chemicals in your spa water. There is no way to avoid using chemicals in your hot tub; therefore, if you want your hot tub to be clean, clear, and safe, you need to maintain it.

In this article, you will find the following; the need for adding chemicals into your water, hot tub chemistry, the need to apply the right chemical for your hot tub, the types of hot tub chemicals that can be used, how to add chemicals to your hot tub, tips on setting up a friendly hot tub mixture, how to store hot tub chemicals, and how to take care of your hot tub.

Hot tub chemicals

Why do I need to use chemicals for my hot tub?

The hot tub temperature is perfect for bacteria to breed and multiply, so the need to use chemicals in your hot tub is not optional. It does not matter how good your filtration is; dirt must still make its way into your hot tub through the air or from bodies that bath/soak in it. The following are reasons why you should make use of chemicals in maintaining your hot tub:

  1. To prevent disease and infection – there are lots of conditions that are attached to poor water maintenance, such as;
    • Coliforms – this disease contaminates the hot tub with fecal matter from the soil as well as feces.
    • Pseudomonas aeruginosa – this disease leads to the numerous outbreak of folliculitis, and it is caused by infection of hair follicles, usually about two days after immersion in pool water. It mainly affects children.
    • Mycobacterium species – this is a respiratory disease that can be contracted in a poorly maintained hot tub.
    • Other infections like the amoeba, parasitic, and other gastrointestinal infections.
  2. To prevent a smelly hot tub, you need to use chlorine chemicals to prevent your hot tub from being stinky.
  3. For cloud-free hot tub water – the use of the right chemicals can help ensure you always have cloudy, milky, and foamy-free hot tub water.
  4. For milky-free hot tub water – you need to use the right chemicals to prevent your hot tub water from becoming milky.
  5. For a foamy-free hot tub – you need to add the appropriate amount and type of chemical into your hot tub water to prevent your water from being foamy.
  6. For a longer-lasting filter, you help destroy germs by using the correct chemicals, thereby reducing the filter’s workload.
  7. For improved efficiency of the hot tub – when you use the proper chemical on your hot tub, you help prevent dirt and debris from entering the hot tub, which makes your hot tub performs better and increases your hot tub’s lifespan.
  8. For good circulation – when you use the correct chemicals properly, it makes the water clean and makes the circulation of water from the pump to the jet and from the jet back to the pump smoother.

All these benefits listed above can be achieved through the following means:

Daily activities

  • Check pH level.
  • Check sanitizer level.
  • Clean water line.

Weekly activities

  • Add hot tub sparkle to keep the water clear.
  • Add No foam to control foaming.
  • Use non – chlorine shock to oxidize your hot tub.
  • Add No Scale to prevent scale deposit (if you live in an area with high calcium hardness).

Monthly activities

Periodical activities

Drain and refill with clean and well-treated water.

What chemicals should I put in my hot tub for the first time?

Steps to setting your hot tub (hot tub chemistry)

Every hot tub requires a balanced chemical level to ensure that the water is always crystal clean and clear. The following are steps you need to follow to ensure that your hot top is chemically balanced

  • Test the water

Testing your water means checking the pH, alkalinity, chlorine level, bromine level, and water’s calcium hardness level. Before testing the water, ensure that the hot tub is not running. They are three primary ways of testing your water.

Use of a test strip – you can use your test strip to determine the PH, alkalinity, calcium hardness level, chlorine bromine level, etc.

Steps on how to use a test strip

  • Bring a glass/transparent cup
  • Go elbow dip into the hot tub, collecting the water from the center to up.
  • Dip the test strip into the water in the glass cup.
  • Pull out and leave for 10 seconds.
  • The test strip bottle is calibrated with color, so you use the back of the bottle to check the PH, alkalinity, calcium hardness, chlorine, bromine level, etc.
  • Record the readings

Use a liquid test kit – a liquid test kit is like an old-fashioned way of checking your water’s pH and chlorine level. It has two compartments, the one for pH and that of chlorine. Phenol red is used to test for pH, while OTO is used to test for chlorine.

Steps on how to use a liquid test kit

  • Put the tester inside the hot tub (elbow deep)
  • Collect water from the hot tub upside down
  • Put four drops of phenol red on the red side for pH
  • Put four drops of OTO to the yellow side for chlorine
  • Cover both sides with their respective cap
  • Shake the tester for like 30 seconds
  • Do not use your fingers to plug up the openings
  • Check the level of the PH and chlorine

Take a sample to your hot tub local dealer – if you think you cannot check the water level by yourself, no worries; all you have to do is

  • Use a clean bottle to collect the water in your hot tub (it should be collected with the bottle upside down)
  • Fill the bottle to the brim.
  • Cover the bottle and take it to your local hot tub dealer
  • Your dealer will test it for you and also give you a recommendation
  • Sanitize

Various germs find their way into your hot tub through the air, insects, and the human body. A sanitizer plays the role of killing these germs and air particles. Sanitizing helps to prevent one from infections like irritation, rashes, respiratory disease, etc.

Every sanitizer has its pros and cons; there are various sanitizers you can choose from to use on your hot tub:

Chlorine sanitizer – chlorine sanitizer kills germs that are present in the water by oxidation.


  • It is very cheap.
  • It is effortless to manage.
  • It kills bacteria.
  • It dissolves fast in water


  • It produces a strong smell when the chlorine is insufficient in the water.
  • It causes dry skin and hair.

NB: Proper chlorine leavel is 1 ppm – 3 ppm

Bromine sanitizer – bromine sanitizer kills the germs that contaminate your hot tub water by ionization (tears contaminants apart)


  • It remains active even after ionization
  • It lasts long before becoming low in the water
  • It is odorless
  • It is safe for people with sensitive skin


  • It is expensive
  • It is unstable (when exposed to sunlight, it begins to burn)
  • It dissolves slowly

NB: The proper level for bromine is 3 ppm – 5 ppm.

Biguanide – this is a non – chlorine sanitizer that helps to destroy the germs present in your hot tub.


  • It has no smell.
  • It makes the hot tub water smoother.
  • It does not require regular usage.
  • It is suitable for people with sensitive skin


  • It is costly
  • It can deteriorate part of the hot tub

NB: The proper biguanide level is 30 ppm – 50 ppm

Minerals – minerals like copper and silver are good sanitizers. Copper acts as an algaecide, while silver acts as a bactericide.


  • It kills germs efficiently
  • It is cheap
  • It is easy to manage

Cons – it also requires the use of chlorine.

NB: The proper level is 0.5 ppm

Saltwater chlorinator – salt serves as a good sanitizer because salt kills germs and pathogens present in the water by converting the salt to chlorine.


  • It kills germs efficiently
  • It saves the cost of buying chlorine
  • It is gentle to the eyes and the body

Cons – it is expensive

NB: In a salt system, the salt level should be 2000 ppm – 3000 pmm, while the chlorine level should be 3 ppm.

Even though you sanitize your water regularly, you also need to shock your water weekly to benefit from an algae-free hot tub. Shocking your water serves as the best way to kill algae and keep your hot tub water clear.

Types of shocks

  • Chlorine shock
  • More bromine shock
  • Non – chlorine shock

There are specific shocks for a particular type of hot tubs

  1. Chlorine hot tub
    • Chlorine shock
    • Non-chlorine shock
  2. Bromine hot tub
    • Chlorine shock
    • More bromine shock
    • Non-chlorine shock
  3. Mineral hot tub – it is recommended because it uses a tiny amount of chlorine non – chlorine shock.
  4. Biguanide hot tub – a biguanide hot tub has its unique shock specifically for it.

NB: After shocking, you need to test the water again to make sure that the water chemical level is balanced

  • Adjust alkalinity levels

when balancing your hot tub chemical level, you need to adjust your alkalinity first before adjusting the pH. To adjust the alkalinity of your water, you will need an alkalinity increaser and a pH decreaser.

Low alkalinity can cause skin and eye irritation, rapid change in pH, and corrosion of metal. In contrast, high alkalinity can lead to scaling formation, skin and eye irritation, cloudy water, and poor sanitizer efficiency. You can adjust alkalinity level with:

  • Alkalinity increaser: You can use an alkalinity increaser to increase the hot tub water’s alkalinity and pH level.
  • Alkalinity decreaser – This is used to decrease your water’s pH; you can also use it to reduce your water’s alkalinity because when the pH of your water drops, the alkalinity also decreases.

The proper level for alkalinity is 100 ppm – 150 ppm

pH scale for spa hot tub
  • Adjust pH levels

After checking and adjusting your alkalinity, you need to pay attention to your pH level. If the pH is too high, it may cause a cloudy, hot tub. If the pH is low, it can damage the hot tub because of its acidity, whereas it can cause scaling if it is high.

High and low pH reading causes cloudy water, poor sanitizer efficiency, skin and eye irritation, and scale formation. You can adjust your pH level by the use of

  • pH increaser – you can use it to increase the pH of your hot tub water.
  • pH decreaser – it is used to decrease your hot tub water’s pH and alkalinity level.

The proper pH level is 7.4 – 7.6.

  • Check for calcium hardness

Calcium hardness is how hard your hot tub water is; if you live in hard water areas, you will notice calcium deposits in showerheads. Hot tub water is expected to be hard water because soft water can eat its way through pipes, tub shell other parts. But if the water hardness becomes high, it can lead to a cloudy, hot tub and scaling.

You can use calcium hardness increaser to increase your hot tub water hardness but, if the water is too hard, you need to drain the water, scrub the hot tub and refill it with treated water.

The proper calcium hardness level is between 75 pmm – 250 pmm

  • Use hot tub enzymes

These are optional chemicals that, when added to your hot tub, break down organic contaminants like oil from the body, leaves, etc. these contaminants, if left for long in your hot tub water, can form scum. The use of enzymes is an optional way of handling contaminants in your hot tub water.

A water clarifier is an excellent temporal means of removing hot tub water contaminants and making the water clear. A clarifier is not a good choice of chemical to use in case of emergency, and it can be the best. In a situation where you want to remove cloudy water with a clarifier, the clarifier will treat the murky water’s symptom and not the cause. When you make use of a clarify, it makes the water clear for some hours, after which it will return to its original cloudy state.

Why you need the right hot tub chemicals

It is essential to use the appropriate chemical for the appropriate problem because when you use the wrong chemical to solve a problem, it creates more problems than a solution. It will not be wise for you to save costs when trying to clean or treat your hot tub because it will end up costing more in the nearest future. The following are problems and the appropriate chemicals to use to solve them;


  • High alkalinity – if your water’s alkalinity is above 100 – 150 PPM, you need to use a PH decreaser to adjust it to its proper level. After adjusting, you will need to test the water to confirm the alkalinity level is stable.
  • Low alkalinity – if your water’s alkalinity is below 100 – 150 PPM, you will need to use an alkalinity increaser to stabilize the alkaline level, after which you will test the water to ensure the alkaline level is average.

pH reading

  • High pH reading – If the hot tub water is above 7.4 – 7.6, it needs to be adjusted using a pH decreaser. Do not forget to test.
  • Low pH reading – When your water’s pH is lower than 7.4 – 7.6, a pH increaser is recommended to increase the pH level back to the proper level.

Calcium hardness

Hard water is water that contains minerals like calcium and magnesium. If you live in areas with hard water, you will typically see mineral residue on the shower top.

High calcium hardness – if your water is very hard, the only way to reduce the hardness is to drain all the water in your hot tub and scrub your hot tub before refilling it with well-treated and clean water.

Low calcium hardness – if your hot tub water is soft, it is dangerous to your hot tub because it can corrode the pipes and other parts. To increase the hardness of your water, you need to use a calcium hardness increaser

Sanitizer level

If your sanitizer level is low, you will need to add more sanitizer to the hot tub water; by doing so, you can help kill the germs in the water and make the filter less loaded. The following are sanitizers that you can use to increase the sanitizer level of your hot tub;

  • Chlorine sanitizer – it kills bacteria that are in your hot tub
  • Bromine sanitizer – it tears contaminants present in your water apart
  • Biguanide sanitizer – this sanitizer is suitable for people who are sensitive to chlorine/ bromine.
  • Mineral sanitizer –this comprises copper and silver sanitizers; they act as algaecide and bactericide.
  • Saltwater – salt acts as a sanitizer with a saltwater chlorinator because it converts the salt into chlorine.


The type of shock used on your hot tub water is dependent on the type of hot tub you have. That is to say, there are some shock that can damage your hot tub instead of solving the problem. The following are different types of a hot tub and the types of shock to use on them

  • Chlorine hot tub
    • Chorine shock
    • More chlorine
    • Non-chlorine shock
  • Bromine hot tub
    • Chlorine shock
    • More bromine
    • Non – chlorine shock
  • Mineral hot tub – you can use non – chlorine shock
  • Biguanide hot tubs – biguanide hot tub has its unique shock designed for it. Therefore if you have a biguanide hot tub, you can only use a biguanide shock.

Dirty pipelines

As you use your hot tub, your hot tub pipes clog; if this clogging is not taken care of, it can block and damage hot tub pipes. You can clean your pipe using line flush cleaner by adding the line cleaner in your hot tub water then drain your hot tub. You should this every three to four-month for a clean and long-lasting pipe.

Effect of using the wrong/cheap chemicals on your hot tub

When you use the wrong chemical or cheap chemical on your hut tub, it causes harm to both the hot tub and anyone that uses the hot tub

Effect on humans

  • It causes body rashes and itches
  • It irritates your eyes.
  • It irritates your skin.
  • It irritates your hair.

Effects on the hot tub

  • It reduces the efficiency of the hot tub.
  • It causes rusting in some parts of the hot tub like pump, jet, pipe, etc.
  • It damages the O – rings and seal for pump, light, and jet.

Steps on how to add chemicals to your hot tub

Some various measures and steps need to be followed when adding chemicals to your hot tub, and they are as follows:

  1. Test the water – Before you add chemicals to your hot tub, you need to turn off the hot tub and test the water. By testing the water, you can determine what is lacking in your hot tub water and which chemicals to add to your hot tub.
  2. Add your chemicals – After testing your water, you will have an idea of the chemicals you need to add; turn on the hot tub, then add the appropriate amount of the needed chemical into your hot tub, then allow the jet to mix it with your hot tub water for like fifteen minutes.
  3. Test the hot tub again – After adding the chemicals into your hot tub and the jet has mixed them properly, you need to recheck the water chemistry to ensure that the chemicals did their work correctly and the chemical level is balanced.

Preventive measures to apply when adding chemicals to your hot tub

There are some measures you need to take before, during, and after adding a chemical to your hot tub, they are;

  • Ensure to turn off your hot tub when testing your water.
  • Ensure the hot tub runs and the jet is on while adding your chemicals to enable the chemicals to mix well.
  • Ensure you keep your hot tub uncovered for at least fifteen minutes after adding your chemicals to avoid hoarding the smell generated by chlorine chemicals when it kills the germs through oxidation.
  • Ensure you turn off the air valves before adding your chemicals into your hot tub water to help the chemicals work effectively.
  • Always make sure you follow the measurement as written in your owner’s manual to avoid using under-dose or overdose of the expected chemical.
  • Ensure you pre-measure the chemicals before adding them into the hot tub water
  • If you have your hot tub indoors, ensure you open the windows before adding chemicals like chlorine because they give up gas when oxidizing the contaminants present in your hot tub.
  • Ensure you retest your hot tub before and after the chemicals have mixed with your hot tub water to ensure that the water chemical level is back to normal.
  • Never add chlorine and bromine to your hot tub simultaneously because when these two chemicals come in contact, they begin to react vigorously, and it is very toxic.

How to store hot tub chemicals

It is essential to ensure that hot tub chemicals are appropriately stored and always out of children’s reach. Some chemicals are sensitive to high and low-temperature change. When some chemicals are exposed to high temperatures, they begin to expand; also, it affects their potency when exposed to shallow temperatures. So it needs to be appropriately stored; you can store hot tub chemicals both indoors and outside.

How to store chemicals indoors

  • Use of a Rubbermaid storage cabinet – This type of storage cabinet is suitable for mounting on a wall; it also has a latch that can be locked. It is kept in a climate-controlled environment. Rubbermaid storage cabinet cannot rust because it is made of plastic, not metal
  • Over the door organizer – You can store your hot tub chemicals with the use of a door organizer. This method helps you arrange the chemicals in their compartments, thereby preventing them from touching each other.

How to store chemicals outside

  • Deck bench hidden storage – This is a park bench, part deck railing which when the flip-up there is a compartment to keep your chemicals, cleaners, etc. problem with this is that since it is outside, it is exposed to extreme temperature. High heat can cause the expansion of the chemicals also; the cold temperature can reduce its potency.
  • Rubbermaid storage cabinet – This type of cabinet is suitable for garages and sheds, and it allows you to store your chemicals and cleaners to be mounting and away from children’s reach. You can also use it to store chemicals indoor.
  • Sterilite Storage Bin – A Sterilite storage bin is a means of storing your chemicals used by many all over the world because it helps you keep the chemicals dry. This storage equipment is very portable; therefore, you can carry your equipment inside in any harsh weather condition. The only minor problem is that when a chemical bottle is tossed into the storage bin, there is a possibility of the chemical spilling.

Hot tub chemical storage tips

  • Always keep the chemicals dry and safe.
  • Ensure you rinse your measurement containers before and after you use them.
  • Keep your hot tub chemical cool between 50 – 75 degrees.
  • Always store sanitizers separately from each other.
  • Store sanitizers separately from chemicals.
  • Keep chemicals out of the reach of children.
  • Never use a self that will not stand in an earthquake.

How to care for your hot tub

It is very important that you use chemicals in your hot tub so that your hot tub is always clean and crystal clear

  1. Fill the hot tub with water
  2. Increase the temperature of your hot tub until it reaches 80 degrees Fahrenheit.
  3. Add enzymes to the water helps kill organic matter and other debris.
  4. Also, add water clarifiers to the water to clear the contaminants in your hot tub water.
  5. Measure your water alkalinity and pH level.
  6. Use an alkalinity increaser to adjust the water alkalinity or use a pH decreaser to reduce the water’s alkalinity depending on the alkalinity level.
  7. Use a pH increaser to increase the water’s pH or use a pH decreaser to decrease the water pH depending on the pH reading.
  8. Add an adequate amount of sanitizers like chlorine or bromine water to your hot tub, or add bromine tablet directly into the floating dispenser system, then wait for thirty minutes.
  9. Use a suitable shock (chlorine shock, non-chlorine shock) to treat your hot tub water.
  10. Retest your water after adding your chemicals to ensure the water chemical level is balanced.
  11. Always take your bath before using your hot tub
  12. Even after using clarifiers on your hot tub, you need to locate and treat the cause of your dirty hot tub.


As a hot tub owner, you need to ensure that you take proper care of your hot tub so that you can continue to enjoy the benefits and pleasure that come with it. All you need to do is test your water daily, adds an alkaline increaser/decreaser, a pH increaser/decreaser, a good sanitizer, shock anti-foamer, enzymes, and clarifier when necessary. If you follow and obey all the guidelines stated above, you will always have clean water.

Leave a Comment