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The Right Order to Add Hot Tub Chemicals

Matt Giovanisci, Founder and CEO of Swim University By Matt Giovanisci | March 16, 2024

What’s the right order to add hot tub chemicals? Adding chemicals in the wrong order can cause cloudy water and prevent them from working. So here’s the right order to add chemicals to your hot tub.

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Do This Before Adding Any Hot Tub Chemicals

Test the water using test strips (or a liquid test kit). You’ll want to check the following levels:

  1. Total Alkalinity, which should be between 100 and 150 PPM. 80 PPM is usually okay.
  2. pH, which should be between 7.4 to 7.6.
  3. Free Chlorine or Bromine. Your chlorine should be between 1 and 3 PPM, or your bromine should be between 3 and 5 PPM. If you use a mineral sanitizer, ozonator, or UV system, these levels only need to be at 0.5 PPM and 1 PPM, respectively.
  4. Calcium Hardness, which should be between 175 and 250 PPM.
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The Hot Tub Chemicals You Should Have On Hand

  1. Alkalinity Increaser
  2. pH Increaser
  3. pH Decreaser
  4. Chlorine or Bromine (I recommend either Chlorine Granules or Bromine Tablets. Chlorine Tablets tend to be a little overpowering for most hot tubs)
  5. Calcium Hardness Increaser
  6. Oxidizer, a.k.a. Non-Chlorine Shock
  7. Chlorine Shock (Yes, this will work in a bromine hot tub too)
  8. A Metal Stain and Scale Preventer (if you need it)

How to Add Hot Tub Chemicals In The Right Order

Be sure to wait 10-20 minutes after adding each chemical to let it circulate and dissipate. Keep your jets on low, the air blower off, and the water heated when you’re adding your chemicals.

Okay, here’s the order I recommend for adjusting your water chemistry. This order works whether you’re starting your hot tub for the first time or just doing weekly maintenance.

If you use a stain and scale preventer, add this before anything.

1. Adjust Your Total Alkalinity First

Your alkalinity helps prevent your pH from fluctuating, so balance this first. If you need to raise your alkalinity, use an alkalinity increaser. If you need to lower your alkalinity, you’ll actually use pH decreased.

You likely won’t see this fluctuate much week to week, but make sure it’s in range before adjusting the other levels.

2. Adjust Your pH Level

Proper pH levels help your sanitizer work more effectively. And when your pH is off, it can cause cloudy water, equipment damage, and skin and eye irritation. This can fluctuate often, especially if you use your hot tub a lot. So, test and adjust your pH weekly.

You can lower your pH with pH decreaser and raise it with pH increaser. If you have issues balancing your pH, be sure to check out our video. 👇

3. Add Chlorine or Bromine To The Hot Tub Water

This is what kills contaminants, bacteria, and algae in your hot tub and what keeps your water sanitary. So, refresh your sanitizer levels each week. That can mean adding chlorine granules directly to the water or adding bromine tablets to a floating dispenser.

If you’re using bromine, it can take a while for these levels to build up in your water. So, if you’re having trouble, be sure to check out our other video on how to use bromine in a hot tub.

4. Adjust Your Calcium Hardness (If Needed)

Poor calcium levels do more damage in the long run, like eroding hot tub surfaces and equipment. But it’s still important to keep on top of these levels, especially if you’ve just refilled your hot tub with fresh water.

And if you have hard water, be sure to use a hose filter when refilling your hot tub.

5. Shock Your Hot Tub

Lastly, you’ll want to shock your water once a week. This helps refresh your sanitizer and kill extra contaminants. You can add either oxidizer, a.k.a. non-chlorine shock, or chlorine shock to your water.

Oxidizer helps keep your chlorine or bromine active and working in the water. But chlorine shock is more powerful and directly kills contaminants.

Either one is fine, even in bromine hot tubs, so it will really depend on your hot tub usage and if you’re noticing issues like cloudy or murky water.

Frequently Asked Questions About Adding Hot Tub Chemicals

I asked around 20,000 hot tub owners if they had any questions about adding chemicals. Here are some of their questions and my answers.

What is the best schedule for adding chemicals to a hot tub?

The schedule for chemicals in a hot tub varies depending on factors like water quality, usage, and the type of chemicals used. It is recommended to test the water regularly (at least twice a week) using a test kit to measure pH, sanitizer levels, and total alkalinity. Based on the test results, adjust the chemical levels accordingly.

What is the most important chemical in a hot tub?

The most important chemical in a hot tub is chlorine or bromine. These chemicals are what kill bacteria and contaminants to make your hot tub safe. Every other chemical is added to support the fighting power of chlorine and bromine. But it’s not the ONLY chemical you should add. You need the other ones for safety and to keep your hot tub lasting longer.

Should jets be on when adding chemicals to the hot tub?

Yes. You should run your hot tub jets on low to help the chemicals mix into the water. I also recommend turning off the air valves. Adding air to the hot tub increases pH.

How warm should the hot tub be before adding chemicals?

Maintain the hot tub temperature between 80°F to 104°F before adding chemicals. The warmer water (and keeping the jets on low) helps the chemicals you add to mix better.

How soon can you go in a hot tub after adding chlorine?

I would wait at least 15 to 20 minutes after adding any chemicals to your hot tub to get it. I would also test the water to make sure all the chemical levels are in range.

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Matt Giovanisci, Founder and CEO of Swim University
Matt Giovanisci is the founder of Swim University® and has been in the pool and spa industry since 1993. Since then, his mission is to make pool and hot tub care easy for everyone. And each year, he continues to help more people with water chemistry, cleaning, and troubleshooting.

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Save Time and Money with Our FREE Hot Tub Cheat Sheet
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