How To: Hot Tub Chemicals

hot tub chemicals

Don’t let the sales pitch fool you. All hot tubs require chemicals to keep the water clean and clear. From a sanitizer to sequestering agent, hot tub chemicals work alongside your filtration system so you can soak safely.

It can feel overwhelming, though, especially if you are new to spa ownership. No one wants to open up the cover to discover cloudy, green, or foamy water. After all, hot tubs are designed to relieve stress — not add to it.

However, when you are trying to establish a water care routine, it can seem like you are spending more time troubleshooting than soaking. 

In this guide, you will learn about  the must-have hot tub chemicals, when to use them, and how to avoid common water problems. 

hot tub chemicals
You should add chlorine to your hot tub after every use and rinse your filters once a week.

Hot Tub Chemical Schedule

Water care does not have to be time-consuming. Taking five to 10 minutes a few times a week can save you time and headaches down the road. 

It’s important to know how often to add hot tub chemicals and set up a water care schedule.  Your hot tub owner’s manual will be the best resource for hot tub chemical questions. You might have to adjust how often you treat your water, though, if you are using your spa more than usual or have guests over.

3x a Week

  • Test the water and adjust total alkalinity and pH (if needed)
  • Check sanitizer and add chlorine (or bromine) as needed


  • Test the water and adjust total alkalinity and pH (if needed)
  • Add non-chlorine shock
  • Rinse hot tub filter

Once a Month

  • Clean your filters as directed by the manufacturer

Must-Have Hot Tub Chemicals

Hot tub owners need basic chemicals for routine water care. However, it’s also important to have products to troubleshoot other water issues. After all, it’s better to be prepared than make an impromptu trip to the spa store. 

Products to Adjust pH

The pH level will tell you how acidic or “basic” your hot tub water is. A high pH can render your sanitizer ineffective, as well as irritate skin and eyes. If the pH is low, the water might  irritate your skin. Low pH can also damage the components of your hot tub. Keep a pH increaser and a pH decreaser on hand.


Even if you have a salt water hot tub, your hot tub will require some sort of sanitizer to get rid of germs and bacteria. Whether it’s bromine, chlorine, or a salt generator, a sanitizer keeps the water clean and safe to use. But when do you add chlorine to your hot tub? It will depend on how often and how many people are using the hot tub. You might add a sanitizer every day or every couple days. Many people opt to add chlorine after each use. Just be sure to leave the jets running and the cover open for about 15 minutes. 

Non-Chlorine Shock

Similar to a sanitizer, a shocking agent releases oxygen into the water. This product raises the total chlorine level above the recommended range but only for a short time. Using a non-chlorine shock weekly will sanitize the water and remove bacteria, chloramines, and other things you don’t want in your water.

Sequestering Agent

Whether it’s called Metal Gon or metal control, a sequestering agent helps remove heavy metals and calcium. You might not think that you have metals in your water. However, depending on where you live, your source water might have copper, nickel, and manganese — even if it’s trace amounts. As metals collect in your hot tub water, it can cause water discoloration. If your water is green, orange, brown, or red, you should use a sequestering agent.


Bubbles are part of a hot tub but you don’t want your spa to look like a bubble bath. Body oils, cosmetics, lotions and other products can cause foamy hot tub water. With regular water — and rinsing off before you can get in the tub — you can prevent foamy water. However, it’s a good idea to have a supply of defoamer.


Your hot tub test strips will also measure calcium hardness, telling you how much magnesium and calcium in the water. Excess calcium can cause foamy hot tub water, as well as scale build-up. If these levels are not balanced, it can also damage metal components. Along with other hot tub chemicals, you should have a calcium hardness increaser and calcium hardness decreaser.

hot tub water
No one wants to discover their hot tub water is dirty and not suitable for soaking. Regular water care and a hot tub cover will keep your water looking crystal clear.

Avoid Hot Tub Water Problems

Many hot tub water problems can be avoided with regular water care and filter maintenance. However, there are times when your water chemistry gets thrown off balance — whether it’s from increased usage or excess body care products.

If you want to avoid water woes, there are some things you can do:

Review manufacturer guidelines. Your manufacturer will advise you as to what products are best for your filtration system. For example, certain filtration mineral systems and bromine are not compatible.

Add chemicals in the proper order. Your chlorine and pH are low? Be sure to balance the pH before adding chlorine.

Rinse off before getting in the hot tub. Whether it’s laundry detergent residue on your swimsuit or body  lotion, the things on your body can affect your water quality. It might feel like a nuisance to rinse off but it can go a long way in keeping your water clean. If you want, consider having a swim suit that you wear only in the hot tub.

Don’t forget about your filters. Clean filters help clean your water. It’s important to rinse your filters regularly, about once a week, and clean them more thoroughly once a month.

Keep your hot tub covered. Your cover will keep out debris and other particulates that you don’t want in your spa, making it easier to keep the water clean.

Hot Tub Chemical Questions

Are all hot tub chemicals the same?

No. Brand to brand, the name, concentration, and instructions can vary. Be sure to read the product label to make sure that it’s right for your spa. 

I have a pool. Can I use the same chemicals in my hot tub?

Pool chemicals, especially when it comes to chlorine, are different from spa products. In addition, you have to keep in mind that a pool holds thousands upon thousands of gallons of water. A hot tub will likely hold less than 500 gallons of water. 

My chemicals are balanced but the water is cloudy. Help!

Cloudy water can be caused by dirty filters or inadequate filtration. Remove your filter and clean according to the manufacturer’s instructions. Old water can also become cloudy; typically, you should drain and refill your spa every six months.

Why does my hot tub smell like chemicals?

Shocking news: If your hot tub water smells, the problem is not the chemicals. Typically, a chemical smell indicates a high level of chloramines — a byproduct that shows your chlorine is working. As long as your pH and alkalinity are in check, consider shocking your water to see if that helps.