SaunaSpy is supported by you, meaning if you buy through our links we may earn an affiliate commision. Learn more.

Ah, a relaxing dip in the spa! Who does not love having a hot tub in the back yard that you can jump in and relax with any time you are feeling stressed or too cold? Spas are a well-loved accessory that many people purchase and install to improve their quality of life. It is easy to see why when you look at how long they last VS how much they cost. Yes, they are expensive! However, when you look at the enjoyment you gain from them and the period they will last, the cost becomes a non-issue.

Taking Care of Your Spa Chemistry, Yuck!

Spa owners around the world all share an annoying hobby… keeping the chemical balance correct, constantly! There is no way to avoid it. If you have a hot tub and want the water to be nice, you must know how to take care of the water. To do this, you will need the correct chemicals and learn how to use them (did I already say constantly?). If you are lucky enough to have the money to afford a ‘spa guy’ (or girl) who takes care of this for you, bravo! For the rest of us, here is the most detailed guide on spa chemicals you will ever see!

Best Spa Water Neutralizer / Metals and Solids Remover – Natural Chemistry 04133 Spa Metal Free, 1-Liter

Our Rating: (5/5)

Natural Chemistry’s Spa Metal Free is the smartest choice for your neutralizing chemical. It comes in a 1-liter bottle and has a very wide mouth so it will not have issues coming out or surging when you are pouring it out.  Metal removing chemicals are either hit or miss, with too many of them not actually removing the metal content from the spa water.

You could easily spend over 100 bucks trying different options only to find out none of them removed all the metals and solids from your hot tub water. This is a common complaint among spa owners! Luckily, Natural Chemistry got it right with this product. It will do the job and remove the copper and other metals present in your water. Compared to some other options, this product is a little more expensive, but it produces the desired result which many other neutralizers simply do not.


  • Powerful chelating agent
  • Does not contain phosphate which can stain
  • Compatible with all surfaces and sanitizers
  • Does not affect water chemistry


  • More expensive than some other options
  • If you have an extra big spa you may need more than one bottle

Top Calcium Hardness Increaser – SpaGuard Spa Calcium Hardness Increaser

Our Rating: (4.5/5)

Spaguard did a great job with their calcium hardness increaser. It comes in a 12 oz 3 pack which is nice and convenient. Calcium levels often get too low, so it is smart to have more than just one bottle on hand for when it is time to amp up the calcium levels. There are several options out there for this job, but this product was by far the most effective and the best deal.

The core of the chemical is granular calcium chloride which is highly effective. It will prevent corrosion of your pump and other equipment due to the low calcium levels that frequently plague your system. It excels at preventing the annoying etching of plaster that tends to happen when calcium levels get too low. Because of the concentrated granular form of the chemical, you will not need much for each use. Only one tablespoon per 100 gallons will increase the calcium hardness by 25ppm!


  • Comes in a convenient 12-ounce 3 pack
  • Granular concentrated form goes further
  • Prevents etching of plaster
  • Prevents damage to equipment due to low calcium levels


  • Not the cheapest option on the market
  • Bottles are not excessively big for what you pay


Best PH / Alkalinity Increaser and Reducer – SpaGuard Balancer Bundle (pH Decreaser, pH Increaser, Alkalinity Increaser, Calcium Increaser)

Our Rating: (4.5/5)

Maintaining the PH level of your hot tub requires both an increaser and a reducer. This would normally require 2 separate purchases. Luckily Spaguard came through again with a solid offering. The ‘Balancer Bundle’ is a great idea and people are loving it. It will allow you to make one purchase and maintain the proper alkalinity in your spa with every chemical you need in one bundle. The bundle includes 4 bottles:

  1. Total alkalinity increaser
  2. PH decreaser
  3. Calcium increaser
  4. PH increaser

The Balancer Bundle is an all-in-one package that will let you increase the alkalinity when your PH levels become too low. The PH increaser will bring the alkalinity levels up when added to your spa. The bundle includes a calcium increaser too which will come in handy. There is also a total alkalinity increaser which is the biggest bottle in the package and will take care of the overall alkalinity deficiencies your water is presenting.


  • All in one pack is convenient
  • Each chemical works well
  • Also comes with calcium increaser
  • Total PH control in one product


  • Bottles are not very big
  • Costs more than lower budget options


Best Chlorine / Bromine Chemical Solution – Clorox Spa 20001CSP Brominating Tablets, 1.5-Pound

Our Rating: (5/5)

As you know there is an ongoing argument about whether to use bromine or chlorine for your main spa chemical. Bromine is preferred for many reasons covered elsewhere in this buyer’s guide. Clorox Spa 20001CSP Brominating Tablets are the best choice by far. The bottle has a wide opening lid which makes it quite easy to pour out the tablets or grab them with tongs. It is a 1.5-pound bottle and contains a large number of tablets, giving you lots of bang for the buck. These are slow dissolving tablets that will sanitize your spa effectively when added to your water. These bromine tablets will also reduce the growth of all types of bacteria that typically grow in spa water. The tablets are designed to be used in your spa floater so they can slowly dissolve over time which is a great set it and forget it solution. There is no assembly needed for this product just drop in the floating basket and you are done.


  • Slow dissolving tablets
  • Reduces bacteria growth
  • Used in spa floater device
  • Lots of product for the cost


  • Tablets sometimes break during shipping
  • Smells different than chlorine

Best Spa Shock – SpaGuard Enhanced Spa Shock 6#

Our Rating: (5/5)

Shock is one of the necessities of owning a spa or pool. It is most often needed after the spa has not been used for a long time and the cover has been on. When you are not using it for extended periods of time, bacteria, metals, and overall nastiness can build up and make the water smell and look bad. SpaGuard Enhanced Spa Shock does a good job of tackling this issue. It is a big bottle that weighs a full 6 pounds and contains plenty of liquid that will be more than enough to shock any spa.

This chemical mixture is compatible with chlorine, bromine, ionization systems as well as ozone. This means it will work with any hot tub setup without issues. It is PH buffered, which means it is designed to prevent any significant changes to the PH balance of your hot tub. Compared to other spa shock products this one is a bit more expensive, but it is the best by far. It is the only product with five full stars in this category.


  • Eliminates contaminates and bacteria
  • Gets nasty green water clear and clean
  • Compatible with all chemicals and set ups
  • PH buffered will not change your PH balance by much
  • Does its job effectively


  • Significantly more expensive (but a bigger bottle)

Top Spa Fragrance Aromatherapy Kit - 3-Pack InSPAration - Spa, Hot Tub, Bath Liquid Aromatherapy Fragrances 9 oz

Our Rating: (4.5/5)

This is completely optional! Fragrances are not needed to keep your spa clean and happy, however, these scents really enhance the experience of relaxing in your spa and are totally worth it! The InSPAration Liquid Aromatherapy Fragrances do this exceptionally well and are not awfully expensive considering what you get for your money.

These come in 34 different smells and when you order you just specify which ones you want in your order. You get 3 per order so pick your favorites. These are our top 8 favorite smells:

  1. Apple
  2. Watermelon
  3. Eucalyptus
  4. Grape
  5. Coconut
  6. Pomegranate
  7. Cucumber
  8. Vanilla

These will not leave any residue on your skin when you get out of the spa, which is a nice benefit to using them over some other choices available. Having a spa session is nice to just kick back and unwind, but when you add some aromatherapy it becomes a much more immersive and effective way to chill out and calm your mind. As we said earlier these are not essential hot tub chemicals but I would not want to have a spa session without them now that I have tried them out.


  • 34 different scents to choose from
  • 3 bottles per order
  • Leaves no residue on skin
  • Strong natural smells


  • Bottles are not big (9 ounces each)
  • Ordering can be confusing (you must message them which scents you want)

Best Spa Chemical Testing Kit - Poolmaster Essential Collection Chemistry Case

Our Rating: (5/5)

If you have a pool or spa you are going to need a good testing kit. There are a ton of cheaply made PH strips and test kits out there, so this was a tough one to find the best. The Poolmaster Essential Collection Chemistry Case is by far the best spa chemical testing kit. It contains the following test chemicals:

  • Bromine/chlorine test
  • PH test
  • Acid and alkalinity test
  • Chlorine neutralizer test
  • Total alkalinity test

It comes with a plastic test block with integrated color chips for accurate matching of colors, which is much better than a cheap paper strip! The entire kit comes in a nice case, so it is easy to store and keep track of all the contents inside. Every test you need to conduct to maintain a healthy spa is included in this package and the tools to do the tests. The entire package is under one pound, so it is lightweight and not too big either. Not only will it test for PH and chlorine amount, but it will also tell you how much active sanitizer is currently in your water. It is an all-in-one solution test kit that has everything you need, and it is a smart design as well.


  • Has everything you need to test for all important chemicals
  • Easy to store in nice case
  • Smart design makes testing easy
  • Not too heavy to carry around


  • Lots of chemicals can be confusing if you do not read the instructions
  • Harder to use than simple litmus strips

Hot Tub Chemistry Explained

To keep a clean fresh spa, you will need to understand the basics of the chemistry involved in the water. There are 8 main types of chemicals involved in this balancing act. The chemicals and chemical types needed are as follows:

  • Neutralizer / metal particle remover
  • Calcium hardness increaser
  • Alkalinity increaser
  • Alkalinity reducer
  • Chlorine or Bromine
  • Shock
  • Optional fragrances

Ideal Chemistry Levels for the Perfect Spa Water

Before we get into all the nerdy important details about spa science, it is important to give you the ideal chemical composition of perfect spa water. You may never achieve these levels of spa nirvana, but this is the recommended range for all the key compounds in your hot tub:

  • Alkalinity: 80-120 ppm
  • pH balance: 7.2-7.8
  • Calcium Hardness: 80-200 ppm
  • Chlorine: 1.5-3.0 ppm (or) Bromine: 3.0-5.0 ppm

Hot Tub Water Neutralizer & Metal Particle Remover Chemical

These types of chemicals are specifically designed to remove harmful metals in your water that will cause damage to the spa and the components that circulate and clean the water. There are many metallic solids that are present in pool and spa water, but the most common ones are:

  • Iron
  • Copper
  • Manganese
  • Chromium

These metals are present in almost all tap water (which is what you fill your spa with!) Over time the presence of these heavy metals will wreak havoc on your pump and internal rubber and plastic parts that filter the water and keep it moving. You will not need to use a neutralizer very often, only when you first fill your spa with fresh water, which should be once or twice per season.

How to Use Spa Neutralizer

When you first fill your hot tub, let the water circulate for an hour or two without putting any chemicals in. Neutralizer will be the first chemical you put in the water before you add bromine or any other chemicals. Follow the instructions on the bottle for how much solution to use for your spa size. Once you add your metal reducer/neutralizer to the water you should let it circulate for a good 4 or 6 hours without adding anything to the water.

Calcium Hardness Increaser Chemical

Calcium is quite common in tap water. If you have never seen it or are not sure what it is, just look at any faucet or showerhead in an area known to have hard water. You will see a white crusty residue around the openings and fittings, this is calcium. On its own, it is not a harmful substance, but too much or too little of it in spa water can be a problem.

Most spa owners do not have a problem with calcium buildup because of the constant use of chlorine or bromine keeps the water soft. When water is too soft it will cause etching and corrosion of the heater element and other equipment, so increasing the calcium hardness is way more common than reducing it in spas.

How to Use Calcium Harness Increasers

Apply the correct amount of the solution (refer to the packaging for this information). Make sure you are using an accurate testing kit to measure the calcium level! Do not pre-dissolve the product before adding it to your spa water, just add it straight from the container or bottle. Any grains that do not dissolve right away, brush them until they are crushed and dissolved. After you have applied the correct amount of the product, run your filtering system for at least 30 minutes. After the 30 minutes have expired test your water’s calcium levels again.

Alkalinity Increaser & Reducer (pH Levels Control)

These are used to control the overall acid or pH levels in your water. Too high of a pH and your water can irritate skin and damage equipment. The ‘perfect’ range for your pH level is between 7.2 and 7.8. If your level goes higher than 7.8 can lead to the formation of scale on your tub and machinery. Be sure you have a good test kit when measuring these levels because it is important to be accurate. When your pH is too high it can also irritate your eyes.

Balancing the pH in your spa has a lot of components to it and there is enough information about it to fill a small book! The most important take away is to know your ideal range and how to use the chemicals to keep your water in the safe range.

How to Use Alkalinity Increaser & Reducers

Like all chemicals, follow the instructions on your product. For most cases, you will simply measure your water’s pH levels with your testing kit and add the appropriate chemical to get the desired outcome. For example, if you test and find that your pH is too high, you will add the reducer in the specified amount described in your bottle. If the pH is too low just add the increaser in the same way.

Bromine or Chlorine Chemicals

These chemicals will be the most frequently purchased hot tub chemicals of all. Typically, these come in wafers or tablets that will sit in a basket that your water filters through when the pump is on. The purpose of them is to kill bacteria in the water. These two chemicals are referred to as sanitizers because they literally sanitize your water on an ongoing basis. Either one of them will do the job but there is an ongoing argument among spa geeks about which is the best. This topic is covered further down the page!

They are harmful poisonous chemicals that you do not want to eat or drink. Too much in your body could do great harm to you. When they are diluted into a spa or pool and used in the right way, they are not harmful to humans or animals and do the job of an anti-bacterial for your water. Spas and pools always have chlorine or bromine circulating in the water. If you open your eyes underwater or spend a long time in a pool or spa you will get itchy skin or blurry eyes when you get out. This is the effect of too much chlorine or bromine being present in the water.

How to Use Chlorine or Bromine

These are quite simple to use. Just look at the container for the recommended amount for your hot tub size and add the tablets (or liquid) to your water. Usually, it will be tablets and you can add them to the little net basket that sits in the reservoir with the floating hatch door. Once the tablets are installed, run your filter system, and let the chemicals circulate for a few hours before using the spa.

Shock Chemicals

These are not used as much as chlorine or bromine, only when your spa seems to be getting too dirty. If you have not used it for a long time and it has been sitting unattended with the cover on for months and months, it can get green and nasty. This is the time to use shock.

Shock chemicals are basically oxidizers that will kill any nasty contaminants and bacteria that your normal treatments did not get. All the stuff that is on your skin when you get in like lotion, oils, hair stuff, etc. will come off your body and into the water. Over time this adds up and can lead to oily nasty water that chlorine alone will not take care of. Shock will do the job!

Types of Shocks

  • Dichlor- The most common type of shock. You can use this without pre-dissolving. This contains some cyanuric acid which will help it against the heat of a spa.
  • Calcium Hypochlorite- The nickname for this one is hypo. This is much better used for pools and is not recommended for spas. It is chlorine-based and cannot stand up to the high temperatures of spas.
  • Non-Chlorine Shock- This is used more often than the hardcore shocks (some recommend weekly). It will kill organic materials present in the water that chlorine misses.
  • Lithium Hypochlorite- Not common. It still shows up in some pool and spa stores, but it is awfully expensive. If you do find it, avoid it. Since dichlor is so widely available and cheap there is no reason to seek out lithium hypochlorite.

How to Use Shocks

Follow the instructions on whichever product you decide to use. For all shocks, the most important part of using them is to let them circulate in the water for the recommended time frame before getting in the spa. These chemicals are serious and will cause harm to your skin and eyes if they are not fully diluted and allowed to circulate and do their job. Some shocks are recommended to use quite frequently (weekly or bi-weekly) while others are only used once per season. Make sure you are using your shock correctly or you may end up having to spend a lot of time fixing your water!

Spa Fragrances / Essential Oils

These are completely optional and are not needed to keep your spa clean and healthy. Fragrances are simply a way to make your spa smell better when you are taking a hot tub bath. They can have some benefits such as calming your mind and relaxing your body. Aromatherapy is widely regarded as a safe way to relax, which goes hand in hand with sitting in a warm spa. Spa aromatherapy and essential oils are inexpensive and really enhance the whole experience.

Chlorine Vs Bromine- Which is Better for My Spa Sanitizer?

Chlorine is a chemical that kills bacteria. When used correctly it will sanitize your spa and is safe.

Bromine produces bromamines which clean your water. It will also do the same job as chlorine and is also considered safe.

So, what is the difference? Chlorine will dissolve faster and needs to be replaced more often. Bromine kills slower and needs less replacing. Bromine will last longer, which means less messing with your sanitizer chemistry.

Bromine is more stable than chlorine and has a lower pH so it helps keep your spa chemistry more balanced over a longer period of time. Many spa nerds prefer bromine over chlorine due to the ease of care it provides.