Test Strips vs Liquid Test Kits For Goldfish Water: Which is Better?

by Adam Till

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Test Strips Are Terrible, Right?

If you have a problem with your goldfish or aquarium water and spend any length of time in an online help group, you'll usually be asked for the results of your water tests taken using a water test kit.

Test kits come in two styles:

  • kits which ask you to take a water sample in a test tube, then add drops to the tube from one or more bottles of liquid testing fluids (called "liquid test kits").
  • kits which ask you to dip a strip of paper containing pads which change colour when immersed in water (called "test strips")

Going back to our example of asking for help on the internet, if you provide people with the results of your water tests and you've chosen to use test strips instead of using a liquid test kit like the one shown above, there's more than a small chance you'll hear one of the following statements:

  • "test strips aren't as accurate as liquid tests"
  • "get a liquid kit, those test strips are a waste of time"
  • "test strips are junk, use liquid tests"

 Are all test strips really less accurate than liquid test kits, however? (Hint: no)

"Test Strips Aren't As Accurate As Liquid Tests"

In my own testing, for everything other than testing ammonia it's just not true that test strips are always less reliable or useful than liquid test kits.

Are some strips better than others? Yes.

Are some liquid kits better than others? Also yes.

Are ALL strips worse than the "gold standard" API liquid test kits? No.

If you have someone tell you otherwise, just ask them if they've done any side-by-side testing of liquid vs strip. If you pressed, I wouldn't be surprised if you found that they've never actually done any.

It definitely is true that the Tetra Ammonia test strips haven't proven to be particularly accurate in my own testing...


...and as a result for testing new tanks or ones that I've added new fish to, I prefer the liquid API Ammonia test kit"

That said, I don't tend to test ammonia on established tanks once I'm consistently getting only nitrates while testing water, so I don't really mind the extra work required to use the liquid kit for this test most times.

Likewise I haven't personally used (but also haven't heard great reports about) the API 5:1 Test Strips

...so I would stick with the Tetra 6:1 Test strips myself if you did want to try test strips.

Finally, if we go to my friend Cory at Aquarium Co-Op for one of his usual great YouTube videos, he'll back me up in saying that the Tetra strips are fine for testing your tank:

In fact, Cory runs his million-dollar business on the back of Tetra strips and liquid ammonia test kits without losing an hour of sleep, so there's really no reason you should worry either.

"Get a Liquid Kit, Those Test Strips Are a Waste of Time"


Anyone who's done water tests on more than one tank using the full range of liquid tests will never argue that test strips are a waste of time.

After all, dipping test strips in even 20 different tanks can be done in less time than it takes to run even a single liquid ammonia test.

Using a test strip is just a matter of dipping the strip into the tank for a few seconds (or to be completely safe, dipping it into a water sample taken from the tank using a drinking glass), then waiting for the colors to settle.

On the other hand, the liquid kits generally require you to measure out 5mL of aquarium water into a clean test tube (do you know where on the curved liquid level to match to the measuring line?), to violently shake at least one and often two bottles of liquid test chemical, to then shake the test tube without it getting on your thumb, and after reading the test to dispose of the chemical solution responsibly. 

So tell me again how dipping a little piece of paper is more work?

The liquid kits are so time consuming that only the most die-hard tester does all the tests every week for each tank.

On the other hand, swiping a strip in the tank is so easy that you actually start to feel a little guilty NOT testing almost every water change.

Comparing Apples To Apples

If you wanted to buy enough liquid test kits to duplicate what the Tetra 6:1 Easystrips test for, that requires doing the following tests:

Since doing even just the nitrate test requires shaking the liquid bottles for over a minute to make sure they're properly mixed, there's no way to argue the strips are a waste of time.

So to each their own, but have fun trying to boil those test tubes and doing the actual tests in less time than it takes to do a strip test...especially if you have more than one tank. 

On that note...

Properly Using Test Tubes

Did you realize that in order to properly use the little glass vials that come with liquid test kits they should be boiled and sterilized between tests?

If you don't, you're leaving residue in the tubes that can contaminate future tests.

How many people who claim that they use liquid kits because they want accuracy do this, do you think? (hint: I've literally never encountered any).

Since I'm a bit of a science nerd at heart and do want to get the most accurate tests I can, I actually DO boil my the tubes I use for my ammonia test between uses.

I don't even have to worry about marking the tube as ammonia or nitrate, since I don't use liquid tests for anything other than ammonia.

Since I'm a lazy little gnome, I bought a dozen extra tubes and only boil them once every tube is dirty (saves quite a bit of time).

Boiling the tubes just means taking a little saucepan from kitchen when your significant other isn't looking (or having one of your own if you're less daring), filling with tap water, adding the tubes and caps (they don't melt, not a worry), and bringing to a full boil. Let them cool, and you're done... place them somewhere to air dry, and they're ready for another set of tests.

If you'd like to do the same, extra API test tubes can be found here:

 If you want to save a bit of money and use regular lab test tubes instead, by all means do so:

 They won't have the little 5ml line marked on them that the API ones do, but the 5ml line isn't actually all that accurate anyway. You can just pick up a handy 5mL or greater dosing syringe and you'll solve that problem in a snap:

Side Note: Is the accuracy of the 5ml Line on API Test Tubes An Issue?

 No, not really.

I've done tests with the test tubes filled to the 5ml line (make sure the bottom of the meniscus or curved part of the water line is at the 5ml line) and I've done tests with a 5ml measured volume using a dosing syringe.

I've never had a difference in reading.

As a result, I'd wager that the test kits are designed to be easy to use, and don't lose too much sleep one way or another.

Speaking on Saving Money...

If you want to half the cost of using test strips instead, just cut each test strip carefully in half using a sharp pair of scissors.

If you're gentle, you can instantly save yourself 50% on testing supplies!

So Are Test Strips Perfect Then?

Nope, they sure aren't.

One of the biggest legitimate criticisms of the test strips is that the color can be hard to interpret. This can be difficult for people with good eyesight, and basically impossible for people who are color blind.

To help everyone, Tetra has come up with a mobile app to help people interpret the tests. You dip the strip, wait for it to change color, and then take a picture of the strip with your mobile phone or tablet.

The app then deciphers the test results for you, and you don't have to be able to see the colors to know what's going on in your tank.

You can find them the app at one of the links here:

That said, color issues aren't just an issue with test strips, since the liquid kits can be just as hard to interpret.

Digital meters that don't output colour are available for things like pH testing:

...but the ones that most people can afford are notoriously difficult to keep calibrated and the expensive ones have expensive probes that must be stored properly to stay usable.

Additionally, to my knowledge it's not even possible to get digital meters for important parameters like nitrate outside of a lab setting, so that doesn't actually solve the problem of non-color based testing entirely anyway.

Free Water Tests At Pet Stores

Worst case, most aquarium shops will test water you bring in for you for free, but then you're at the mercy of the staff doing the tests correctly, and having clean test tubes available.

I haven't had good results getting reliable tests at any store I've visited, unfortunately (though that's not to say that no store tests are reliable if yours is really competent). When I've had to bring a water sample in to claim a dead fish warranty, inevitably the water comes out with high nitrites, or nitrates or something else.

When I ask them to retests with a clean vial, the water inevitably tests out fine.

Tetra Strips and the "Brown Nitrate Strip" Issue

Some people have found that their nitrate test pad on the Tetra strips is discolored straight out of the bottle. This seems to be an issue that comes from absorbing moisture from the air, and is worse for humid climates and for people that don't tightly screw on the caps.

If you see this issue on a new bottle, you can probably return for a refund.

I've found that the strip is still accurate to a usable degree even in this condition, so I don't worry about it personally. As long as I can tell that my nitrates haven't crept above 40ppm, that's about all I care about myself.

In Conclusion: Tetra EasyStrips Make Easy Work Of Water Testing

In a nutshell, the people who complain the most about the accuracy of test strips usually haven't even used them, and are just repeating things they've heard other people say.

Test strips aren't perfect, but good ones like the Tetra 6:1 Test Strips are more than reliable enough for even commercial operations like Arctic Lights Aquatics' goldfish breeding program or Aquarium Co-Op's retail store to depend on them.

If you want to given them a try AND save a bit of money in the process, in addition to the trick I mentioned earlier about cutting them in half down the long side, just do like we do and buy the 100-count pack.

It's often much cheaper overall compared to the smaller pack, and should last you for a while:

So in the end, if you have a few tanks to test or just don't want to spend an hour shaking test vials and boiling glass tubes, I highly suggest strips over liquid kits (and adding an API ammonia test kit for new tanks).

Do you use liquid kits or test strips?

Do you have a favourite brand?

Please leave me a note in the comments and tell me about it, I've love to hear form you.

Need help interpreting your water tests? Check out my handy step-by-step guide to interpreting test results here.

Adam Till
Adam Till


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