Best Saltwater Aquarium Test Kit

Best Saltwater Aquarium Test Kit | 2022 Reviews

If you want to build a beautiful aquarium and keep it alive, you need to use testing kits. If there is too much ammonia, nitrite, or acidity, your plants and fish might die.

Don’t try to keep your aquarium healthy without testing the water. Even experienced aquarium builders rely on testing kits to detect problems before they get any worse. Test often when you have a new tank and periodically later on.

Some saltwater aquarium testing kits are better than others. Some kits are more accurate, cheaper, and easier to use.

If you regularly use a good testing kit, you can keep specific nutrients within a certain range and prevent them from going too high or too low. Calcium, magnesium, and phosphate are three crucial minerals you need to keep in balance.

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Best Saltwater Test Kit Reviews

A good saltwater test kit should test for as many different parameters as possible. Not every kit will test for everything.

API Saltwater Master Test Kit

The API Saltwater Master Test Kit is affordable, reliable, and includes the most critical tests. This kit tests for everything that will kill your fish sooner rather than later. The API kit is one of the best testing kits on the market because it covers everything crucial.

The API kit lets you test for ammonia, nitrite, nitrate, and pH. Nothing will kill your fish faster than too much ammonia or nitrite. If the pH is either too high or too low, this can also kill your fish quickly.

The API kit is a liquid testing kit, so it has six bottles of testing liquid, four testing tubes, testing strips, and an instruction booklet. The instructions are clear and straightforward, so you should not have any trouble with this kit if you have never tested aquarium water before.

After you finish with your solution, sample, and test strips, the strips will change color. You will then compare the test strips to a color chart to know if your parameters are in the correct range.

Red Sea Marine Care Test Kit 

The Red Sea Marine Care Test Kit is a very accurate test with an easy-to-read color card. You will place the test tube in a white circle on the color card before comparing the colors.

It is hard to know what reading to take with some other testing kits because the color can look different from different angles. With the Red Sea Kit, you know exactly what angle to compare the colors from, so it easy to get the same result that anyone else would.

As well as a standard pH test (which can measure either alkalinity or acidity), the Red Sea Kit also has a test specifically for alkalinity. The alkalinity test is helpful if you are having trouble with the water becoming too alkaline but never becoming too acidic.

This testing kit works for both freshwater and saltwater, so if you switch to a freshwater tank, you can still use your testing strips. You can do very many tests with this kit before you run out.

The kit lets you take precise measurements. You can measure ammonia within 0.02 PPM and nitrate with an accuracy of 0.05 PPM. Tests for pH and alkalinity are also exact.

Salifert Master Reef Testing Combo Kit 

The Salifert Master Reef Testing Combo Kit lets you test magnesium, calcium, and phosphate in addition to the usual pH and nitrate. If you have a coral reef tank, it is particularly important to know how much magnesium, calcium, and phosphate is in your tank.

While the test does not let you differentiate between fairly low and near-zero nitrate, the test is still accurate. Long before the level of nitrate or phosphate becomes unhealthy, this test will detect it.

A flaw is that the kit does not test for ammonia or nitrite. For this reason, don’t use the Salifert test on its own. Get a different test kit that tests for ammonia and nitrate in addition to the Salifert test.

The Salifert test is a good choice as it is a cheap and accurate way to measure calcium, magnesium, and phosphate. Many other tests do not measure these minerals, which are essential for the health of a reef tank.

Calcium, magnesium, and phosphate all matter. Low calcium won’t kill your fish nearly as fast as high ammonia, but in the long run, your fish may weaken and die without calcium and magnesium.

Aqualuna Aquarium Test Strips

With six tests per strip and 100 tests before you run out, you can test your tank very often for a low price. The testing strips are also very easy to use – just dip them in your tank for a couple of seconds and then wait a minute for the strips to change color. Compare the strips to the color chart to see whether your nitrate levels or pH levels are correct.

The Aqualuna Aquarium Test Kit test for nitrite, nitrate, chlorine, carbonate, water hardness, and pH levels. Testing for chlorine, carbonate, and water hardness is not as common as testing for more dangerous ammonia or nitrite, but these tests are still valuable.

Harder water is usually good for fish, as it helps them grow bones and tissues. Some species of fish may need softer water to survive. In nature, there is a vast range of water hardness.

A lot of tap water is chlorinated, which can hurt your fish. Test your water for chlorine once in a while and find a different water source if the chlorine levels are not very low.

The strips also test for carbonate hardness. High carbonate hardness will lead to high pH if you do not take care of it. You can prevent high pH before it starts if you do carbonate tests.

Capetsma Aquarium Test Strips

Capetsma Aquarium Test Strips are another good choice if you want to test some uncommon substances, such as iron and copper. The kit accurately measures nine parameters (Copper, Iron, pH, nitrate, nitrite, carbonate, general hardness, alkalinity, chlorine). The strips are good for two years as long as you do not expose them to very hot or very cold temperatures.

While the strips test for many different things, they do not test for ammonia, which may be the most dangerous thing that can build up in an aquarium. Use the Capetsma strips in addition to another kit that measures ammonia. Often, you need to make two purchases to get kits that test for everything you want.

Since the strips are cheap, you can use them weekly for a long time without running out. The strips are also quick to use, so they are a great choice if you want to test frequently.

Milliard Aquarium Test Strips

The Millard Aquarium Test Strips are another great choice if you want cheap but accurate tests. Even if you check your water more than once a week, it will still take all year to run out of strips, and even then, it is cheap to buy more.

Like many other testing kits, it lacks an ammonia test. Make sure you get some ammonia testing strips elsewhere. Many tanks never develop a problem with ammonia, but you can suddenly lose a few fish if they do.

You can test for pH, nitrate, nitrite, alkalinity, hardness, and carbonate. The strips are quick and easy to use, and the company’s customer service is very responsive if you are having any trouble.

BOSIKE Aquarium Test Strips

The BOSIKE Aquarium Test Strips are easier to use than any other strips I have tried without lacking accuracy. You simply dip the strip in your water for two seconds, wait for 60 seconds, and then compare the colors. The strips are as accurate as more expensive and time-consuming testing methods.

You can get 125 strips in a single inexpensive bottle. The strips work for water in general, not only in aquariums. The colors do not bleed and ruin your tests, and the paper is durable and will not get soggy after you get it wet.

While almost all of the BOSIKE tests work for saltwater, one of them does not, and that is the water hardness test. You will need to get different strips to test water hardness in a saltwater tank.

Parameters You Need to Test in a Saltwater Aquarium

There are at least ten different things you need to test for in your fish tank. If you skip a few tests, you could run into trouble with plants dying, fish dying, or algae growth. (There’s a reason many people think that it’s harder to maintain a saltwater tank.)

Don’t skip tests for “less important” parameters. It takes longer to fix problems than to prevent them.

It takes much longer to correct the damage that might occur if you don’t do regular tests. Even if your tank has been stable for a long time, you should occasionally do a full test and measure everything.


Alkalinity is the opposite of acidity. Like acidity, it is measured on the PH scale. An extremely acidic substance has a PH of 0, and an extremely alkaline substance a PH of 14.

The acidity in an aquarium will never be near either extreme, but smaller changes in pH can harm your fish. Pure water has an alkalinity of 7 – neither acidic nor alkaline. You need to keep the alkalinity in a narrow range, or else your aquarium will have problems.

If you are building a coral reef aquarium, you need a bit of alkalinity. More neutral is not always better – a pH of 7 can be too alkaline or too acidic for some fish to thrive. An alkaline pH between 7.6 and 8.4 helps the coral calcify and is necessary for bone growth in saltwater organisms.

Both natural and artificial marine ecosystems get their alkalinity from carbonate and bicarbonate. If the alkalinity is too low for a coral reef aquarium, you can add sodium bicarbonate and other chemicals to the water to keep it in the right range. Don’t overdo it – high alkalinity can kill the life in your tank or cause limestone to form.

Regularly test your tank because it doesn’t always take long for the pH to swing too high or too low. Alkalinity matters enough that you might get an alkalinity meter and not mere test strips.


Ammonia is one of the most harmful substances that can build up in your tank. Ammonia will kill all fish, though it takes longer to kill some species than others. Ammonia is a poison, and enough of it would kill a human.

Fish produce ammonia when they breathe through their gills. You have to do what is necessary to keep the ammonia level down. While bacteria will eat ammonia and turn it into nitrate, nitrate is also harmful to fish.

Usually, you can keep ammonia levels down only by changing the water. This will also get rid of nitrates. If this is not enough, you can add plants that feed on ammonia.

When you test for ammonia, you should ideally test zero. Your nitrate tests won’t test zero and don’t have to, but ammonia is more dangerous and easier to minimize.


Calcium is also necessary for fish. You can add calcium to a tank by adding coral, but this is not always enough.

Too much calcium can cause your fish to behave oddly and only grow to a small size. Very high levels of calcium can kill everything in your tank. Test for calcium and keep it in the right range.

Your fish can and should get calcium from food., but this is not always enough for your fish. You can add liquid calcium as well.

When putting liquid additives into your tank, be careful. Don’t pour it into your tank directly from the bottle, as you might add too much that way.

Pour it into a measuring cup first so that you know how much you are adding. Too much calcium can clog your filters as well as hurt your fish. Some people also use eggshells as a source of calcium, but I find it a hassle to clean the shells out of my tank.


Magnesium is found naturally in seawater and is a necessary mineral for living things of all kinds. Humans, land animals, and sea animals all need magnesium because cellular reactions depend on it.

Magnesium is also important because it prevents the precipitation of other minerals. Calcium and bicarbonate will solidify if magnesium is too low. This will clog your filters.

Your tank’s pH can also become too low (acidic) if there is not enough magnesium in it. If you have a reef aquarium, magnesium should be three times more abundant than calcium to keep your reef animals healthy.

The calcium to magnesium ratio should be similar to what you find in a natural coral reef. You should also keep your magnesium between 1250 and 1350 ppm, as seawater naturally has 1285ppm of magnesium.


While nitrate is not nearly as dangerous as ammonia, it is still harmful to fish. Fish won’t grow properly or reproduce if nitrate levels are too high.

Tap water often contains nitrate, and you may need another source of water. You should keep nitrate as low as possible – fish don’t need it, so lower is better.

Anything over 100ppm of nitrate is harmful to fish. You may want to keep nitrate below 50, 25, or 10 ppm.

10ppm will not kill your fish, but it may cause algae to grow too quickly. If you want your fish to reproduce as much as possible, keep the level below 10ppm.

Changing the water often may keep nitrate levels low. If that is not enough, you can add plants that reduce nitrate.

Check out our article for the best nitrate removers!


Ammonia is the most dangerous, followed by nitrite and, lastly, nitrate. Fish, plants, and bacteria can convert ammonia into nitrite and nitrate into relatively safe nitrate over time.

Like ammonia and unlike nitrate, nitrite can kill a lot of your fish quickly. High nitrite often coincides with or shortly after high ammonia, and both can poison your fish.

Nitrite poisoning makes your fish unable to breathe even though there is enough oxygen in the water. If your fish seem to be struggling to breathe, test for nitrite.

It is crucial to test for nitrite when you set up a new tank, when your filter has had any problems recently, and when your fish seem sick. If your fish are moving their gills rapidly, they are having trouble breathing.

If your nitrite is too high, replace most rather than some of the water in your tank. You can also keep nitrite down by removing food your fish don’t eat and adding more aquarium salt to the water.


pH is the alkalinity or acidity of the water in your tank. Different fish prefer different pH levels.

It can harm fish to move them to a tank with a different pH suddenly. Ideally, the two tanks should be within 0.2 pH of each other. Saltwater fish need a higher (more alkaline) pH, and freshwater fish need a more acidic pH.

In the sea, pH is mostly stable. In a closed environment like a tank, the pH can go too low or too high easily. Test the pH at least once every two weeks, and always test the pH if your fish are having trouble.

Insufficient air filtration will make the pH change. If your filter is not working well, carbon dioxide will build up and make the water acidic. Natural processes in fish and plants can also produce acids that raise the pH gradually.

You can use baking soda to raise the pH and use vinegar to lower it. You can also buy pH control solutions. If you want to spend a bit more money to save time, you can buy a calcium reactor to keep the pH stable.


Phosphate is one of the less dangerous substances that can build up in your tank. While it is relatively harmless, it can still indirectly harm your fish.

Phosphate does not hurt fish; instead, it causes algae to grow. The algae will eventually use up too much oxygen, so you should control phosphate.

So many different things raise the level of phosphate that you can’t keep it near zero. Fish wastes, decaying plants, tap water, and many things you add to your fish tank raise the level of phosphates. Overfeeding your fish is not a good idea – the decaying food will raise the level of phosphates.

Usually, you should not use chemicals to control phosphates because they are not dangerous enough. Instead, get a filter with phosphate absorbers and keep your filter clean.


You also have to balance the amount of salt in your aquarium. How much salt you need depends on what fish and plants you have. Most saltwater tanks should have a salinity of about 30ppm, compared to less than 0.5ppm for a freshwater tank.

Different testing kits offer different instruments. You might want to buy a hydrometer or refractometer separately to get the most accurate measurements.

Hydrometers are the cheapest way to measure salt levels and are usually good enough unless you want to invest in the most accurate equipment you can find.

A hydrometer is a glass tube that you place in your tank. You can measure the salinity by how deep the tube sinks. This works because salt affects how well the tube will float.

You can also buy more expensive refractometers to measure salt levels. Refractometers, some but not all of which are digital, use light to measure how much salt is in the water. The level of salt determines how much light bends when it passes through the water.


Fish are more sensitive to temperature changes than humans are. If the temperature changes by only five degrees for a relatively short period of time, some of your fish might die.

Ideally, the temperature should not change by more than 2 degrees in 24 hours. A reef aquarium should be 78 to 80 degrees or 77 to 83 degrees. Sometimes a temperature change won’t do any harm; other times, it will kill fish.

If you have trouble keeping the temperature stable, you can get a heater or a chiller. These devices keep your temperature stable automatically.

You may be able to keep the temperature stable by placing the tank in a good location. Don’t place it right beside a sunny window – the light will heat up the tank, and the temperature will change by too much each day. Install a thermometer in your tank to measure the temperature whenever you want.

How Often Should You Test Your Saltwater Fish Tank?

Testing once a week, at least in the short run, is a good idea. Many people test more than once a week at the start. Test often to make sure that your new tank is stable.

In the long run, many aquarists do not test the water as often. If your tests always turn out well and your fish seem healthy, you might test only monthly. (See our guide on how to clean a saltwater tank.)

Beginners should test more often. Experienced aquarists are less likely to make mistakes that push any parameters too low or too high.

If you have enough experience, you can usually tell that the tank is healthy just by looking at it. If there have been any problems recently, check the tank more often.

Frequently Asked Questions About Aquarium Test Kits

You should keep track of the temperature, ammonia, nitrite, and pH. Your fish can die quickly if these things are out of balance. Everything else also matters, but it won’t kill your fish as quickly.

Yes, the newer your tank is, the more often you should test the water. Testing twice or more times per week for the first month might be a good idea.

Later on, you can cut down to weekly or monthly. If everything is going well, you do not have to be paranoid.

Yes, but it takes a long time. Many testing kits have expiry dates written on them. Usually, it takes years rather than months for a testing kit to expire.

Both liquid testing kits and testing meters are accurate enough to keep your fish alive. Meters are the best, but testing kits will also work. While some testing strips may not be very good, proper testing kits that use testing liquid are accurate.

Liquid testing kits are the best option until you choose to invest in meters. If you will be keeping an aquarium for many years, it makes sense to switch to testing meters eventually.

While meters can save you money in the long run, beginners do not like having to invest much money. Use liquid testing kits until you are sure you will stick with your aquarium hobby for a long time.

Final Thoughts about the Best Saltwater Aquarium Test Kit

Be careful when you first start running an aquarium. Run the tests often, read the instructions, do everything slowly and carefully. Later on, keeping your tank healthy will become instinctive, and only an occasional quick test will be necessary. 

Looking for more gear for your aquarium? Head over to our Aquarium Gear section to see more reviews.

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