How to Use Hot Tub Test Strips

By Calvin | Last Updated: May 29, 2021 | Guides / How To

When you purchase a hot tub, you automatically accept a set of hot tub maintenance tasks. One task that you will need to do more times than others is testing the water in the hot tub.

You will frequently need to test the pH levels of the water, the calcium hardness, the chlorine levels, and so much more. There are different ways to test the water in your hot tub but by far the easiest method is to use hot tub test strips.

Hot tub test strips are a cheap and convenient way to test the water in your hot tub but how do you use hot tub test strips? Let’s find out. First, let’s check out why you need to test the water in the hot tub.

If you have a hot tub, then you probably know what test strips are. But, do you know how to use hot tub test strips? The process is very easy, and we explained it all in this post.

Why Should You Test the Water in The Hot Tub?

You should test the water in your spa or hot tub frequently to know what is going on in your hot tub. Hot tubs need a certain level of calcium hardness, acidity, and sanitizer levels. Testing the water makes you know if your hot tub water has the needed level of chemicals and water properties.

Testing the hot tub water is also important to diagnose a problem in the hot tub. You may notice that the water in the hot tub is turning green or it’s having a brown tint on the surface, or maybe the water is cloudy.

Most of these problems are caused by unbalanced water chemistry. So, to know how to fix the problem, the first step is to find out what is causing the problem. This means you need to test the water in the hot tub.

During the lifespan of your hot tub, you will find yourself testing the water at least once a week. So let’s check out how to use hot tub test strips.

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How to Use Hot Tub Test Strips

Using hot tub test strips is a very simple process. All you need is to identify colors and you are good to go. Don’t believe me? Let’s dive deeper.

To use hot tub test strips, the first thing to do is to:

Collect a Sample of Water

You need to use a clean bowl to collect a sample of the water in the hot tub. Most people just go ahead and dip the test strip into the large hot tub water and use that as an accurate reading.

Don't dip the test strip into the hot tub water. Instead, collect the water and put it in a bowl.

While there is nothing wrong with dipping the test strip in the hot tub water directly, you wouldn’t be guaranteed the best result. This is because when you dip the test strip into the hot tub water, you will most likely do so by dipping the test strip in the water around the shell of the hot tub.

The water around the shell and the jets wouldn’t give you the most accurate reading. This is because the water there is usually unbalanced, to say the least. The best part of your hot tub to take a sample from is the middle of the hot tub.

Dip the Test Strip in the Sample Collected

The next thing to do is to dip a test strip in the sample of water collected. You need to do this quickly so the test strip doesn’t get soaked. Hot tub test strips usually have directions on each strip that indicate where to hold and where to dip into the water.

Now, dip the test strip into the bucket of water.

When you dip the test strip in the water, do not swirl it around. This will only damage the test strip. Not to mention that you would not even get any reading close to being accurate. Also, don’t flick the test strip when you take it out of the water. That might mix the colors.

Hold Still

When you take out the test strip, do not shake it or move about with it. Just hold still for about 20 seconds for the test strip to get an accurate reading.

Hold the test strip into the water for 20 seconds.

After about 20 seconds, you will notice a color pop on the test strip. The color is the result of your water test but you need to interpret what the color means.

Compare the Test Strip to the Color Guide

All test strips usually come with a color guide. The color guide is usually on the container of the test strip. The color guide has several different colors like green, yellow, and red.

Compare the Test Strip to the Color Guide

Note: The color may vary depending on your test strip model.

Each color has its meaning. So compare the color you got on your test strip to get a match on the color guide. The color match tells you what the color you got means.

For instance, if you were testing for total chlorine levels and the test strip shows a green color, it means that the total chlorine in your hot tub is very high. If it’s yellow, then it’s very low. So just compare the color you got to the color guide. It’s as easy as that.

Here are the number of how your hot tub chemistry levels should be:

Dispose of the Test Strip and Adjust the Water Chemistry Accordingly

After you have tested the water, use the results of the reading to adjust the water chemistry accordingly. Then you can dispose of the test strip.

Why Should You Use Hot Tub Test Strips?

Hot tub test strips are the most common method of testing hot tub water and for good reasons.

Hot Tub Test Strips Are Cheap

For starters, hot tub test strips are cheap. They are by far the cheapest option available to test the water in your hot tub. I purchased my Pool and Spa test strips for just $11 and it has 7 strips in the bottle.

Most test strips have a price tag between $10 and $15. Most liquid testing kits will cost you more than that and don’t even get me started on the cost of digital testing kits.

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They Are Easy to Use

Hot tub test strips aren’t only cheap, they are also easy to use. I just have to dip a test strip in a sample of water and compare the color I got on the strip to the color guide. It’s as simple as that.

Hot Tub Test Strips Give Quick Results

With hot tub test strips, you can test the water and get the reading in less than a minute. Most other methods will take you longer.

Hot Tub Test Strips Are Accurate

What’s better than getting a quick test result? Getting an accurate result. Though hot tub test strips are not the most accurate water testing kits, they can still give a very accurate reading if used correctly.

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Can I Use Chlorine Test Strips for Bromine?

Yes, you can. I have used chlorine test strips in a friend’s bromine hot tub and I got an accurate reading. One thing you need to know is that both chlorine and bromine are sanitizers. So, if you use a chlorine test strip in a bromine hot tub, you will still get an accurate reading.

The same thing goes for bromine test strips and chlorine hot tubs. The test strips are used to measure the sanitizer level in the hot tub and are not specific to a type of sanitizer.

But, if you want to be a hundred percent sure, you can check the color guide of the test strips you purchased.

On the color guide, the colors for each water property and chemical are usually indicated. Most test strips give chlorine and bromine reading by using the same colors and numbers. If that’s the case with your test strip, then that means it can be used to test both bromine and chlorine levels in the water.

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What Does Free Chlorine Mean on a Test Strip?

Free chlorine in simple terms refers to the level of chlorine that is yet to be used in the water. This is the chlorine that we test for in the hot tub. When you add chlorine to the water, the chlorine doesn’t just dissolve in the water. It is gradually used up in the water by killing bacteria and breaking down scum.

The free chlorine reading that you get on the test strip refers to the amount of chlorine that is still in the water. It is also known as active chlorine. This means that the active chlorine is free to get rid of bacteria and germs in the water.

Free chlorine is very important when testing the chlorine levels in the water. If you don’t have enough free chlorine in the water, then you don’t have enough sanitizer to get rid of the bacteria and other contaminants that can get into the water. The right range for free chlorine in the hot tub is between 1ppm and 3ppm.

What Does Combined Chlorine Mean on a Test Strip?

Combined chlorine refers to the amount of chlorine that has been used up in the water. It’s the combined chlorine that produces the nasty smells, eye irritation, and the likes that you notice when you add chlorine to the water.

When chlorine comes in contact with organic matter like hair and body oils in the water, the chlorine binds together with the organic material to form combined chlorine which is also known as chloramines. The right range for combined chlorine in your hot tub water should be 0ppm.

Any reading more than 0.5ppm means that there is too much scum in the water indicating that the chlorine is being used up quickly.

When you have too much scum, then the reading of the combined chlorine will be high and this usually means that the hot tub needs to be shocked or a high dose of chlorine needs to be added to the water to balance things up.

What Does Total Chlorine Mean?

Total chlorine is the addition of free chlorine and combined chlorine in the water. Most hot tub owners test for total chlorine in the water but in most cases, that’s the wrong thing to do.

This is because total chlorine only shows you the addition of the free chlorine and combined chlorine in the water. It doesn’t distinguish the two or let you know the level of each type of chlorine.

So, if you have combined chlorine in your hot tub water and you go ahead to test for total chlorine, the test result will be useless unless you know how much combined chlorine you have in the water first.

The only time to test for total chlorine is when you are sure that there is no combined chlorine in the water. That way, you can use the reading of the total chlorine to know how much free chlorine is in the water.

You can also use total chlorine to know how much combined chlorine is in the water. You just need to know how much free chlorine is in the water first. Then you can do the math by subtracting the free chlorine from total chlorine to get the combined chlorine. I’m sure you get it now.

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Final Words

Overall, hot tub test strips are very easy to use. Like I stated earlier, all you need to know is how to match colors and you are good to go. The test strips will do the rest.

Now you know how to use hot tub test strips, you can go ahead to test the water in your hot tub. As an expert tip, always test the water in the hot tub at least once every week. This will help you keep track of your water chemistry and be on top of the situation at all times.

Hi, I'm Calvin Hall, the owner of Hot Tub Wiki. I worked at a local Spa Service for a few years before creating this website. I have owned several hot tubs and fixed a thousand of them. So, I know a thing or two about hot tubs.