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Hot Tub Chemicals Glossary

There are lots of hot tub chemicals used in keeping your hot tub clean and clear, and sometimes we don’t always know what those chemicals are or what those terms mean!

So, we’ve compiled a list below of hot tub chemicals with their definitions. If you don’t see a term you’re looking for or still have questions, please feel free to contact us anytime.

Hot Tub Chemicals List

Take a look at the alphabetical list of hot tub chemicals and their definitions that are associated with your spa:


Alkalinity is the concentration of alkaline materials in your hot tub water. Alkaline materials can control or buffer your spa’s pH level. You can lower the alkalinity with pH down, and raise the alkalinity with Alkalinity Plus. Keep your alkalinity levels between 100-150ppm.


Biguanide is a generic name of some popular non-chlorine/non-bromine chemical sanitizers used in spas. They are popular alternatives to traditional chlorine sanitizers.


Bromine is a sanitizer that kills bacteria in hot tubs. It can be added to your spa in the form of chemical dispenser, floater, or tablets. When your spa is refilled, granular bromine is established in the water with a bromine reserve- so you don’t need to wait days for tablets to dissolve in the hot tub feeder.


Calcium are scale deposits that form within your hot tub plumbing, or on the shell of your hot tub. This happens when the water in your tub is imbalanced, or your pH levels are too high. Ideal calcium level in your spa is 180-250oom.


Chlorine is one of the preferred sanitizers to use in your hot tub – bromine being the other. It is sold in granular, liquid, and chlorine formats. In hot tubs, di-chlor should be used (not tri-chlor, which you use in pools).


Hot tub clarifiers are designed to clear up cloudy water, keep your pH balanced, and make sure your filter is running properly – such as SpaBoss Spa Clear.


Defoamer is a chemical used to eliminate or reduce (temporarily) foam in your spa water. When your water foams, it typically means there are too many soaps, oils, detergents, etc., in the water. If you want the particulates reduced, you should get a clarifier (as mentioned in the definition above). If you want them temporarily eliminated until you can get a clarifier, use a defoamer.


Enzymes are biodegradable proteins that break down different pollutants in your hot tub (oil, film, detergents, etc.)

Filter Cleaner

A filter cleaner is used to clean your hot tubs filter without using harsh acids or bleach. It removes and loosens all debris, oil, hair, grime, etc., that becomes lodged in the filter.


There are a handful of different minerals in spa water that include potassium, calcium, and sodium. You can have a hot tub mineral system in your spa which includes silver and copper. Copper is used to combat algae, while silver kills bacteria and destroys fungi.

Non-Chlorine Shock

Non-Chlorine Shock is potassium peroxymonosulfate, which is used to activate chlorine/bromine in water, as well as shock your water.


pH stands for potential hydrogen, and it measures active acidity in your spa water. The scale of pH is between 0 – 14, with 7 being neutral and anything under 7 resulting in corrosion of your hot tub/plumbing, body irritation, breakdown of alkalinity, and loss of chlorine/bromine. High pH in your spa can result in the same types of issues – so the preferred pH range is between 7.2-7.6.


Sanitizers kill microorganisms and bacteria in hot water. Bromine and chlorine are the most popular types of sanitizers used. Chlorine is used most often to disinfect water. Bromine lasts longer as it has a higher chemical temperature than chlorine. Bromine does dissolve slower on startup, however, so it usually takes a couple days to establish proper reserve in your hot tub water.

Sequestering agent

The sequestering agent is a chemical agent that removes ions from water and forms a ring. The clumps left over can then be filtered out of the water using the hot tub filter. Different names for sequestering agents include stain and scale control and metal gone.


Shocking your water can help bring back free chlorine/free bromine into your water to disinfect it (as often as needed or at least once a week). Non-chlorine shock, also known as potassium monopersulfate, is used in spas as it doesn’t kill bacteria, but it burns off chloramines/bromamines by releasing oxygen into the water. You can use an extreme shock called superchlorination, but you must wait until the chlorine levels are below 5ppm to go back into the water.


Stabilizers are typically composed of cyanuric acid which binds to chlorine molecules. They reduce the amount of chlorine needed to keep your water safe. Additionally, these bonds make chlorine more effective at eliminating bacteria and germs.

Water Treatment / Conditioner

Water conditioners are enzymes that are used to remove the food source for bacteria from the water. They additionally help to maintain your spa water’s pH balance.