Pool Test Kits vs Test Strips. Which is Better for Pool Water Testing?

Updated Jun 1, 2021

Weekly pool waster testing is pretty much a must if you want to keep your water balanced. But how do you choose between pool test kits or pool test strips? You even have multiple types of pool test kits to choose from, so how do you make the right decision on your success when it comes to testing you water?

So, how do you choose?

There is an unbelievable battle between too much information and just enough information to make an informed decision. The most important tool in your pool maintenance strategy.

pool water testing kits strips

Liquid Pool Test Kits or Pool Test Strips, which option is better?

Honestly, it just comes down to personal preference.

We have put together some basic information about both options to give you enough of an idea to make your own decision as to which might be best for you.

Liquid Pool Test Kits

There are basically 2 Main Types

Type #1: OTO Pool Water Testing Kit

(chemical name, orthotolidine) and phenol red.

For this test kit, you will use two containers to sample your water into, both chlorine and pH levels can be determined after adding your reagent drops into the water samples.

Typically, you will do 3-5 drops on each side, and notice the water change color and those shades of color will determine your Total Chlorine and pH levels. Compare those color shades to the chart that comes with the kit.

 

And, the 2nd option…

Type #2: DPD Pool Water Testing Kit

(N N Diethyl-p-Phenylenediamene)

The DPD Test uses the same kind of water sampling, reagent drops, and color shade referencing.

However, you will get a more accurate results using this test, and you can also measure Free Chlorine, in addition to Total Chlorine.

Free Chlorine is the effective and useful form of Chlorine.

 

Now’s the part where you ask…

“What in the world is FREE Chlorine compared to TOTAL Chlorine?

Chlorine just needs to go in the pool and presto… it works, right?”

 

Well, that would be great, but there’s more than one type of chlorine in your pool water.

There’s actually 3 of them. 

Wait!!! Where did the third option come from?

 

The key to keeping your pool properly sanitized and safe for anyone who wants to swim in it… is that you really need to understand the difference between Total Chlorine, Free Chlorine, and… Combined Chlorine.

Combined Chlorine?

Isn’t that the same as Total Chlorine?

Not really!

Let us explain…

Free Chlorine

When adding chlorine to your pool, it dissolves and forms HOCI, which is technically called, “hypochlorous acid

Free Chlorine is the type that is usually tested to determine the appropriate chlorine levels in your pool water – this is the amount of chlorine that’s still able to sanitize your water.

The Free Chlorine is the Chlorinated Water that hasn’t interacted with any other contaminants in the water. It’s essentially, “Free and Ready” to attack any contaminants that plan to hit the water.

When measuring with your pool test kits, make sure that the Free Chlorine is between 1.0 and 3.0 parts per million (ppm).

Once the Free Chlorine reacts with contaminants in the water, it becomes Combined Chlorine.

Combined Chlorine

Combined Chlorine is the chlorine that has already been “used up” by  sanitizing the water.

When chlorine in the pool water encounters organic material, such as body oils, urine or sweat, it attacks (sterilizes) those organic materials. And that sterilization process creates something we call, “chloramines.”

Once chloramine is formed, it means the sterilization process has come and gone the free chlorine’s ability to disinfect is pretty much over.

Well, technically it takes about 24-25 parts of Combined Chlorine to do the same job as 1 part of Free Chlorine. So, pretty much useless.

Combined chlorine also has a very strong chlorine smell that turns your eyes red and irritates your skin if you jump into the pool.

If you are smelling an overwhelming chlorine smell coming from your pool, you need to check your chemistry balance.

It does NOT mean you already have too much chlorine. That is a misconception. Most likely you used up your chlorine and have too much combined chlorine.

So, use your pool test kits or pool test strips to stay on top of things.

You can calculate combined chlorine (CC) levels by subtracting the free chlorine (FC) from total chlorine (TC) in your pool.

How Do I Remove Combined Chlorine?

Keep your Free Chlorine at the proper levels and combined chlorine will typically work itself out.

However, if you figure out the math on the combined chlorine, just add 8-10x of free chlorine to remove it.

Total Chlorine

Equal to the sum of the Free and Combined Chlorine in your pool water.

CC + FC = TC

Put It All Together

If you’re testing the total chlorine and free chlorine levels and they turn out to be the same, this means you don’t have any combined chlorine in your water… meaning you have not used any chlorine yet.

If those pool water test kits or pool test strips show total chlorine level is higher than the free chlorine level, you take the difference between the two levels to find the level of the combined chlorine.

If you want to ensure your pool is sanitized and ready for swimming, the free chlorine level has to stay above the combined chlorine level.

Free Chlorine Means You Can Swim Without Worry!

All you need to do is make sure you keep the right amount of Free Chlorine in your pool to keep it perfect for swimming.

A pool that is not sanitized… is a disaster waiting to happen.

So, unless you happen to have a smart chemistry management system to handle your pool water testing, be sure to stay on top of those chlorine levels, and be a consistent pool tester, using whatever chlorine tester you decide to us, so you and your friends should be good to go whenever you decide to take a dip in the water.

Now that you know all about Chlorine… Let’s get back to the pros and cons of the 2 liquid pool test kits.

OTO Pool Test Kit

Pros:

Accurate if you use the correct number of drops and follow the instructions on the OTO pool water testing kits.

Cons:

If you mess up on the drops, even if by a little bit, your results will not be accurate.

More time-consuming and attention to detail is necessary.

You wont be able to see the Free Chlorine levels.

The OTO Reagent is also a known carcinogen, which is never a good thing to interact with.

DPD Pool Test Kit

Pros:

Use the correct number of drops and follow the instructions on the DPD pool water testing kit and get accurate results.

This kit DOES show Free Chlorine level, but NOT the Total Chlorine Amount

DPD pool testers measure a lot more levels than OTO kit.

Cons:

Same issue with messing up the drops… if you mess them up… your results will not be accurate.

High levels of combined chlorine may create false positives for free chlorine.

Costs more than OTO test kit.

Much more involved and take patience and attention to detail.

There are many popular test kit brands you may have already heard of, including: Taylor Pool Test Kits, Aquachek Test Kits, LaMotte Test Kits, Poolmaster Test Kits, and HTH Test Kits.

All of which also have their pros and cons… but at least now you know enough of the basics of liquid test kits now to determine which one you might need.

Now, onto the Pool Test Strips, which are significantly growing in popularity…

Depending upon how these are used, swimming pool test strips can be just as accurate and even have less chance of messing up samples than even the best pool test kits.

Since all you need to do is dip the pool test strips into the water and compare them to a color chart… this by far, is the quicker and easier than the liquid pool test kits methods.

Test strips also have the ability to test for much more than the 2 types of liquid pool test kits combined…

You can find calcium hardness test strips, phosphate test strips, bromine test strips, chlorine stabilizer test strips, pool pH test strips, Free Chlorine test strips, Total Chlorine test strips and Combined Chlorine test strips, as well as other awesome chemicals to keep your pool or spa in tip-top shape.

Here are some quick pros and cons on pool test strips…

Pool Water Testing Strips

Pros:

Most Test Strips are simple to use… and it’s just about impossible to mess up readings

These strips have so many more levels you can check vs the test kits listed above i.e. (calcium hardness, cyanuric acid test, biguanide test, salt, etc.).

Cons:

They can sometimes be harder to read, only because they are smaller than the pool water testing kits.

You can find many popular test strip brands you may have already heard of, including: Aquachek Test Strips, Clorox Pool Test Strips, and HTH Pool Test Strips.

Generally speaking, both of these test pool water testing methods have their pros and cons, but testing ultimately falls into your comfort level.

So long as you use the water testers according to the manufacturers’ guidelines, it is best to choose the type you are most comfortable and have the most confidence using.

We recommend that you take your water to a pool professional or pool retailer to use quality test equipment. This way you can cross-check your results and ensure accuracy periodically.

No matter which type of pool testing you prefer to use, here are some additional guidelines and recommendations to keep results accurate:

Always use fresh strips or reagents.

Check the manufacturer’s guidelines for how long these pool test kits and pool test strips are expected to be accurate. Most manufacturers will recommend disposing of pool test kits reagents after 1 year and pool test strips after 2 years.

NEVER USE OUTDATED POOL SUPPLIES!

Avoid storing any test strips or reagents with extreme temperature or high humidity conditions

A temperature range of 40°- 85° F is the general consensus. Pool water test strips or pool test kits reagents are best kept in a drawer inside your home.

Be sure to store all pool test kits, pool test strips and keep liquid reagents out of direct sunlight.

UV light begin to degrade the product and prolonged exposure to sunlight will fade the color charts and results.

Keep all containers tightly sealed or capped.

If you leave any containers open, everything will oxidize and screw up your test results.

Retest any readings if you are getting inconsistent results.

Although chemicals change over time, it’s possible that even the best testing supplies and equipment can sometimes misread.

The key to good quality testing is to use good quality test products. Using them correctly, testing your water consistently at home (2x per week).

Maintaining your routine will result in a cleaner, crystal blue pool and the increased knowledge with chemicals and maintenance process.

Conclusion

Anyways, we hope the test kit vs test strip info was useful. We have been testing pool water for some time now and found that the above recommendations should get you up to speed on testing pool water.