The Best Aquarium Test Kits Available on the Market Today

Charlie Morton

Charlie Morton


best aquarium test kit

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When it comes to testing aquarium water parameters, you’ve got two main options: liquid test kits (aka. drop test kits), and test strips.

While test strips are sufficient for offering quick, approximate readings, liquid test kits offer a more accurate and reliable method to test both freshwater and saltwater aquariums.

But which liquid test kit is the best? We checked out four of the top-selling brands to find out.

API Freshwater Master Test Kit

API Water Test Kit
  • Accurately monitors 5 most vital water parameters levels in freshwater aquariums: pH, high range pH, ammonia, nitrite, nitrate
  • Designed for use in freshwater aquariums only
  • Use for weekly monitoring and when water or fish problems appear

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The API Masters Kits have been setting the industry standard for aquarium drop test kits for years.

With a reputation for being more accurate than test strips, this 4in1 test kit, tests freshwater aquarium water for pH (with an additional test for high pH), ammonia, nitrite, and nitrate levels.

Fairly easy to use, simply fill your test tubes up to the line with your water sample and add your drops of test solution to each tube and watch them change color.

The color card that comes as part of the kit offers very detailed readings, with each parameter measured in small increments.

As a slight drawback, API Master Kits lack GH, KH, or chlorine tests, the kits for which need to be tested separately.

Each kit gives you more than 800 tests, meaning the kit will last longer than test strip packs.

Things We Like:

  • A tried and trusted water test kit, used by professionals around the world.
  • Exceptional accuracy and reliability.
  • More economical if you’re testing often.

Things We Don’t:

  • GH, KH, and chlorine tests need to be purchased separately.
  • A little more time-consuming than test strips.

Fluval Master Test Kit for Aquarium Water

Fluval Master Test Kit for Aquarium Water
  • Offers essential testing of pH, Ammonia, Nitrite and Nitrate
  • Measure water parameters to maintain a balanced and healthy environment for your fish and plant life
  • Quick and accurate testing for safe water conditions
  • Made in Canada
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Fluval is a premier aquarium brand, best known for its outstanding filters. But their liquid test kits seem less well known.

This 4-in-1 Master Kit for freshwater and saltwater measures water pH, ammonia and ammonium, nitrites, and nitrates. In other words, it tests the same water parameters as the API Master Kit.

Instead of having two separate tests for regular pH and high pH, this kit simply contains a ‘wide pH’ test, which ranges from pH 5.0-9.5. That’s a wider range than most test kits offer, but it comes at the expense of being divided into larger increments.

Whereas The API Master Kit measures pH down to as little as 0.2 increments, this kit only offers 0.5 increments.

This compromises a tiny bit of accuracy, but still, 0.5 increments in pH should be sufficient for most aquarium owners.

These test kits are made in Canada and, overall, customers seem fairly satisfied with the results.

Things We Like:

  • A decent 4-in-1 liquid test kit from a trusted brand.
  • Suitable for saltwater as well as freshwater.
  • Wide range pH test eliminates the need for a second pH test.

Things We Don’t:

  • Less tried and tested than the API Master Kit
  • 0.5 pH increments may not satisfy those looking for high precision!
  • Lacking GH, KH & chlorine tests.

Sera Aqua-Test Box (+ Cu) Aquarium Test Kit

Sera Aqua-Test Box (+ Cu) Aquarium Test Kits
  • Master test kit
  • Includes all the important test kits
  • Very accurate
  • Tests easy to read
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This 9-in-1 box kit offers a comprehensive set of tests from Sera, a reputable specialist in aquarium equipment.

The tests included in the box are for pH value (pH) total hardness (GH) carbonate hardness (KH) ammonium/ammonia (NH4/NH3) nitrite (NO2) nitrate (NO3) phosphate (PO4) iron (Fe) and copper (Cu).

Along with the usual water parameter tests, phosphate tests are useful for controlling algae levels, as well as for coral reef aquariums.

Copper tests are useful when treating fish with copper-based medications, and iron tests are important for diagnosing iron deficiency in live plants.

This means you’d rarely have to go out to buy any additional test kits, except perhaps for chlorine, CO2, and dissolved oxygen, which this kit doesn’t include.

Not surprisingly, you have to pay for all the extra tests, so this kit is substantially more expensive than the standard 4-in-1 liquid test kits.

Things We Like:

  • A comprehensive test kit, testing a wide range of parameters.
  • Made to a high standard by a trusted company.

Things We Don’t:

  • Some of the tests may be superfluous for many aquarium owners.
  • More expensive than simple test kits.

Nutrafin Master Test Kit

Nutrafin Master Test Kit
  • Master Test Kit; Ensures your fish are living a proper environment
  • Includes all Hagen test kits including ammonia, pH, calcium, phosphate, iron, nitrite, nitrate, KH and GH
  • Easy-to-read color charts are included
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Another fairly comprehensive kit, the Nutrafin Master Test Kit for freshwater and saltwater tanks includes Hagen tests for pH, KH, GH, ammonia and ammonium, nitrite, nitrate, phosphate, iron, and calcium.

This is exactly the same 9 parameters as the Sera Aqua Test Box offers, except for a calcium test in place of the copper tests, which makes it useful for reef tanks and planted tanks!

The kit also comes with 5 glass test tubes with caps, 2 pipettes, 1 spoon, and 4 instruction booklets.

Some users have expressed frustrations over test tube caps coming loose and slightly vague color cards, but in general, this is a well-made kit that’s especially useful for marine and reef tank users.

Things We Like:

  • Comprehensive test kit for 9 different parameters.
  • Especially useful for marine aquariums.

Things We Don’t:

  • Some small quibbles about some components.
  • More expensive than the basic test kits.

All About Liquid Aquarium Test Kits

Whether you’re new to fish keeping or have been keeping fish for decades, you need to test your water regularly. Even in a large, established aquarium, you need to be testing parameters at least once a month.

Why Testing Your Water Is Important

Whether you’re keeping pet fish, snails, shrimp, amphibians, or turtles, all aquatic animals are sensitive to water chemistry.

Each species has its own preferences for pH and water hardness, as well as the trace amounts of toxins like ammonia and nitrites that they can tolerate.

These last two are especially critical since ammonia and nitrites can both kill fish within a matter of days and should always be kept at zero.

Testing Water in a New Aquarium

When you set up a new aquarium, it needs to go through a period known as ‘cycling’ before it’s ready to use.

Cycling is basically the process of building up colonies of beneficial bacteria within the tank’s filter and substrate that can convert deadly ammonia and nitrites to nitrates. Depending on your method, cycling can take anywhere between two weeks to two months to complete.

Obviously, testing during this time is vital to find out if the beneficial bacteria are making progress and to determine when the water is safe to introduce your fish.

After the first fish go in, it’s not unusual to test the aquarium water every one or two days to make sure that conditions are settled.

How Often To Test Water in an Established Aquarium

Recommendations for how frequently you test your water in a seasoned tank vary from once a week to once a month.

For an established large aquarium that’s well-stabilized, monthly testing will likely suffice. But for smaller tanks where water parameters can change rapidly, weekly or bi-weekly testing is advised.

Water testing is also your first port of call when you have any problems with your fish’s health or aquarium filter. Even if you have diagnosed a disease or health condition, water parameters can often be a contributing factor to diseases, and correcting water conditions may be essential to aiding your fish’s recovery.

Likewise, if you’ve had a problem with your filter, the beneficial bacteria that remove toxins might have been affected, meaning you need to test regularly for ammonia and nitrites to keep your fish safe.

Aquarium Liquid Test Kits vs Aquarium Test Strips

There is a lot of debate about whether liquid test kits or test strips make a better choice for the average aquarist, so let’s take a closer look at the details.

Accuracy and Reliability

When it comes to accuracy and reliability, there’s little doubt that liquid test kits come out on top.

The API Master Test Kit in particular is renowned for being the most reliable and popular test kit in the industry and is often used as the standard with which to measure the accuracy of other kits.

One of the reasons for this is that the API Master Kit measures water parameters in such precise increments. On the pH color chart for example, it measures pH in increments of 0.2 between each slight shade of color, allowing you to get a very precise reading compared to most test strips.

Ease of Use

In terms of ease of use, test strips win hands down. While liquid tests may be more precise, they do take longer to complete. Each test must be performed in a separate tube, with exactly the right amount of water and drops of test solution for the test to be valid.

When it’s as simple as dipping a strip into your water and waiting one minute to observe the color readings for multiple parameters at once, test strips have mastered the art of simple testing that you can (almost!) do with your eyes closed.


The value of each test kit differs, but taking the API Master Kit for an example liquid test, the kit contains over 800 tests – which will last the average fish keeper a long time!

Many aquarists report never even finishing all of the bottles.

API’s test strips, which cost around 75% of the price of a Master Kit, only offer 100 tests. Although the number of test strips can be sneakily doubled by cutting them in half, a mere 200 tests for almost the same price as a package that offers you 800 tests means liquid tests are more economical if you’re doing a lot of testing.

So, Which Is Better: Liquid Test Kits or Test Strips?

If you’ve just got a single aquarium and want a quick and easy test to get a rough idea of your water parameter values, test strips offer an easy solution.

If you’re looking to get more accurate readings from the most reliable source, though, then API liquid test kits are the way to go. If you’re carrying out lots of tests, they’ll likely save you some money too.

Check out this helpful video for an unbiased comparison between test strips and test kits here.

Which Water Parameters Aquarium Kits Test For

PH (Potential Hydrogen)

One of the most important water parameters to test for is pH. Each fish and aquatic pet has its own requirements for a pH range to remain in optimum health.

Whereas fish from the Amazon tend to prefer acidic-neutral water, with a pH of 6-7, fish from calcareous regions such as African cichlids need a high pH of between 7.5-8-5. Aquatic snails need a neutral–alkaline pH to retain healthy, robust shells.

Since materials and compounds in your fish tank such as limestone rocks, pieces of driftwood, and carbon dioxide can affect your water’s chemistry, you need to test pH regularly to ensure it remains within the correct parameters.

GH (General Hardness)

GH stands for general hardness and is measured in dGH (degrees of general hardness). GH is the sum total of all the particles dissolved in the water. 1 dGH is equivalent to 17.9 ppm.

Fish that prefer soft water such as neon tetra require a water hardness of less than 10 dGH (<179 ppm), whereas hard water fish like mollies prefer a GH of between 12-25 dGH (215-447 ppm).

KH (Carbonate Hardness)

KH stands for carbonate hardness and is a measure of how many carbonates (CO3) and bicarbonates (HCO3) are dissolved in your water.

These compounds are responsible for neutralizing acid that is created in your aquarium, and act as a protective barrier or buffer against your tank becoming acidic. The higher your KH, the more stable your neutral-alkaline water conditions will be.

Ammonia and Ammonium (NH3 and NH4)

Ammonia is a nitrogenous compound that is expelled into the water by fish waste, uneaten fish food, and dead plant matter.

Since even small amounts are deadly poisonous to fish and invertebrates, aquarists must always aim to keep ammonia levels at zero. This is why biological filtration and proper cycling are so important.

But if you have a problem with your filter or notice your fish with red eyes or sore-looking gills, you can test your water for an ammonia spike – an emergency situation in an aquarium that needs rectifying immediately.

Nitrites (NO2)

Like ammonia, nitrite is another nitrogenous compound that needs to be kept at zero for the well-being of your fish. Nitrite poisoning results in fish with brown-colored gills breathing fast and struggling to obtain enough oxygen.

Just like ammonia poisoning, it demands an immediate response to avoid disaster. This is why test kits can save your fish’s lives!

Nitrates (NO3)

When ammonia and nitrites are converted by beneficial bacteria in your biological filter, they turn into nitrates. Nitrates are much less harmful to fish than ammonia and nitrites and small amounts of nitrates are also essential for plant growth.

If nitrate tests reveal that levels are too high (over 20 ppm) however, they can become toxic for fish and encourage algae blooms, requiring you to increase water changes and improve aquarium hygiene.

Phosphates (PO4)

Like nitrates, phosphates are ultimately produced by decaying fish waste, uneaten food, and plant materials.

Small levels of phosphates in freshwater aquariums (up to 1 ppm) are beneficial for plant growth, but beyond this, phosphates only encourage algal blooms – leading to cloudy water and oxygen depletion.

In marine tanks, even low levels of phosphates can be problematic, encouraging harmful algae, and causing corals to turn brown.

Iron (Fe)

Iron is an essential mineral for plant growth. If your live plants are turning yellow or pale, you should test the water for an iron deficiency. Iron supplements for planted tanks are readily available online.

Copper (Cu)

Copper testing is useful in conjunction with a copper-based medication to treat various fish diseases.

Firstly, the copper testing kit is used to ensure copper levels are kept high enough over several weeks to eliminate the infection.

Once the infection has been neutralized, tests can confirm that copper levels have returned to safe levels for invertebrates such as shrimp and snails to be reintroduced.

Calcium (Ca)

Calcium is an essential element in reef aquariums because corals, crustaceans, mollusks, and even some types of beneficial algae need calcium to grow.

Like iron, calcium is also an important nutrient for freshwater planted tanks. A calcium test is used to check that calcium levels are optimum for invertebrate and plant growth.

Water Tests That May Need To Be Purchased Separately

Carbon dioxide, dissolved oxygen, and chlorine tests are also frequently sought after by aquarists, but for those, you’d typically need to buy a separate set.

CO2 tests are essential if you’re using a carbon dioxide injection system to boost plant growth in an aquascaped aquarium.

Oxygen test kits are used when fish are showing signs of hypoxia or oxygen depletion.

And chlorine tests are useful to understand whether your aquarium water conditioner is working properly to remove chlorine and chloramine from your tap water.


Do Aquarium Test Kits Have an Expiry Date?

Yes, they do! API Master Test Kits typically come with an expiry date that gives you 5 years to use them.

If you have a very old API Test Kit, it may not have an expiry date, but only a date of manufacture disguised in the Lot number. For example, Lot # 28A0107 indicates a date of production in January 2007. Way too old to use!

Test strips usually have a shelf life of around 2 years when left unopened, but will expire faster than that after opening.

How Can I Adjust My pH and Water Hardness Values?

If you’ve tested your water and it’s too acidic or too alkaline for your fish, there are some tricks you can use to adjust the pH to your required level.

Adding driftwood, Indian almond leaves, and peat are some common ways that aquarists add tannins to their aquariums to reduce pH.

To raise pH, adding limestone, sustainably-sourced crushed coral or baking soda are popular tricks to make an aquarium more alkaline.

How Do Aquarium Test Kits Compare to Digital pH Meters?

Digital pH meters are becoming increasingly popular to give fast, accurate pH readings in aquariums. But make sure you buy electronic tests from a reputable manufacturer as there’s a great variation in quality.

Digital meters also only usually measure pH, rather than all the other parameters that test kits do. Even if TDS (conductivity tests) are available, they only offer a very vague reading of water hardness compared to GH and KH tests.

Our Top Pick

Without a doubt, the hands-down winner for the best liquid aquarium test kit for freshwater aquariums goes to The API Master Kit.

Having set the industry standard for many years, API produces a liquid test that you can count on to give incredibly accurate results.

If you have a heavily planted aquascape tank or a marine aquarium, then you could consider the Nutrafin Master Test Kit, which tests water hardness, phosphates, iron, and calcium levels in addition to the four basic tests that API offers.

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