Everything You Need to Know About pH Testers

With so many pH testers available on the market today, the possibilities are endless. The accuracy of the pH testers differ between brands, and the need for accuracy depends on the tolerance levels of your fish and other inhabitants of your fish tank.

The best pH tester for water depends on what you are trying to determine.  For beginners or those with sensitive fish tank residents, the best option for you is either using testing strips or the testing kits.  These tests will not only give you the pH reading but test for many other elements as well. 

For hardy fish and hobbyists that understand what affects the pH having a digital reader is better and more accurate.  For those who want to know the elements inside the aquarium who have some experience with reefing the kits are fun to work with and will give you quality information. 

What is pH?

pH testers measure if a solution is alkaline (solutions which have more hydroxide ions), or acidic (solutions which have hydrogen ions) of the water in your fish tank.  pH 7 is a solution that has the same amount of hydroxide ions and hydrogen ions.

pH changes In Your Aquarium

The nitrogen cycle changes the pH level of your water inside your aquarium.  Water changes will increase or decrease the pH levels depending on the KH and GH of the water in your fish tank.

Fish waste is broken down into either ionized ammonium (NH4), which is safe for fish or un-ionized ammonia (NH3), making the water toxic.

If your water has lower pH levels, this indicates higher levels of ammonium (NH4), and higher levels indicate high ammonia (NH3).  High pH levels are dangerous, and that is why monitoring your pH is vital for fish keeping.

Bacteria feed on ammonia and convert it into nitrites, and another bacteria convert nitrites into nitrates.  Plants clean the water of nitrates and are important to the nitrogen cycle and lower CO2 levels in your tank, which in turn increase the KH levels consider having a planted aquarium.   

If you want to add plants to your aquarium, find out How To Care For Aquarium Plants to help you decide if you want to add them to your fish tank. 

A cycled fish tank has enough bacteria (Nitrosomonas and Nitrobacter), and these bacteria will only survive in a tank with the pH levels between 5 – 7.2 for freshwater and 7.2 – 8.5 for saltwater fish tanks.  If these levels drop or increase outside of these levels, your nitrogen cycle is destroyed.  Most fish, plants, and bacteria tolerate levels between 7.2 – 8.0 to keep all the elements doing their job well.

Safely Increasing and Lowering the pH Level in Your Fish Tank

The pH levels in your fish tank may change depending on the nitrogen cycle and what is happening inside your fish tank.  From time to time, you may have to adjust the pH levels in your aquarium.

To increase the pH levels of your fish tank:

  • Aeration which increases the oxygen in your fish tank
  • Adding crushed coral increase KH and help prevent pH shock.
  • Adding shells as part of your decoration

To decrease pH levels of your fish tank:

  • Complete a 10% – 30% water change depending on the level you need to decrease

If the water from your faucet is out of the pH parameters using RODI water will help.  There are portable machines, devices that need a dedicated water supply, or you can buy RODI water.  Mixing RODI water with regular water until you find the right balance will further reduce costs.   If you are using only RODI water in a freshwater fish tank, you have to remineralize it.

Also read – How to Use RODI Water to Create the Best Water for Your Aquarium

It is better to keep the levels in your tank consistent, and weekly water changes and cleaning will do just that.  pH levels between fish and plants differ, research to find out which ones are suitable for your fish tank.

Hobbyists need to understand the nitrogen changes in the tank, and testing PH, Nitrates, Nitrites, Ammonia, Temperature TDS, KH, and GH is vital. 

Once the levels of the tank are consistent, and the environment is stable, testing, PH, and temperature will suffice.  Record these levels, and you will see a trend.  If you note a change in either of these levels, further testing can be done to determine the cause. 

Also read – How to Choose the Best Aquarium Heater in 2020

Adding a new element to the aquarium, including but not limited to, a new filter, fish, plants, and changes to food or increasing the amount of food.  Additional testing is advised to gauge how this element affects the nitrogen cycle. 

There are different pH testers on the market. Digital pH meters. In addition to using a digital pH meter in aquariums, they are suitable as a hydroponic pH meter, a drinking water pH tester, and a soil pH meter. Digital pH meters in this article are the pH pen meters as they are portable and easier to use.

Other pH testers include testing strips that test the other elements in the fish tank in varying combinations of PH, nitrates, nitrites, carbonate, free chlorine, total alkalinity, iron, copper, hardness, mercury, lead, manganese, fluoride.

The final type of pH testers is a solution based one.  As the vials and solutions are separate, you can conduct a pH test of your aquarium water on its own.  The pH testers from API and Redsea are available as separate purchases. If you are looking for value for money, the combination of testing kits work out less expensive.

pH testers that are a digital pH meter can be used for aquarium enthusiasts and aquaponics for both the soil and water depending on the system you have created. 

Testing solutions

pH testers that use solutions to test pH levels entail filling vials with water from the center of your tank.  Rinse out the vials with water from your fish tank to remove trace elements that may contaminate the pH test. 

Fill with fresh fish tank water before adding the correct amount of solution and mix, wait the required time and compare the colors of the liquid to the colors on the chart to determine the level of pH.  After empty the vials and clean with distilled/RODI water.

Brands and different test differ between the amount of solution you need to add, the mixing of the solutions, and the reaction time.  Read instructions carefully to understand how to use each one.


The API master test kits have several variants that test different types of water, available, and each test for different elements.  The KH and GH tests are not included in these kits.  They can be purchased separately and are essential elements to keep a stable environment.

The API master test kits include:

  • Freshwater kit test for pH, high range pH, ammonia, nitrite, nitrate
  • Saltwater kit test for pH, ammonia, nitrite, and nitrate
  • Saltwater and food kit tests for pH, ammonia, nitrite, and nitrate
  • Reef kit tests for calcium, carbonate, water hardness, and Phosphate
  • Pond kit tests for pH, Ammonia content, Nitrite levels, and Phosphate

The amount of product used per tests differ and separate replacement bottles are available.  The API tests kit refills include not only the solution but the bottles as well, which is useful if you have broken yours.  Extra vials and the KH and GH kit can be purchased separately.  If you add a syringe, then it is similar to the Redsea kit and costs less.

See this product in action with this video.

There are two problems with this kit; it does not test for hardness and KH, which have to be purchased separately.

API Test Kit GH and KH Tests

There are separate kits to select the correct one for your requirements.  This test kit may be more accurate, but it is a time-consuming test.  It is value for money as you have more tests per kit than with a bottle of strips and the solutions last two years.  If you have multiple fish tanks, it may not be practical. 

Purchasing additional vials is a good idea; you may drop one, or if you have multiple tanks, it will save you time to do all the tests at the same time.  Clean the vials out with distilled water before and after testing for more accurate results.

If you have a pond, you may want to check out our article 8 Best Pond Pump for the Most Satisfying Fish Keeping Experience.

API Replacement Test Tubes with Caps

Additional vials for the API master kit can be purchased separately and will give you an additional 24 vials to use with your solutions.


  • Accuracy
  • Value for money


  • Glass vials
  • Time-consuming

Our verdict:  This pH tester is accurate, and if that is your main purpose, this kit is affordable as an initial expense.  Add in the KH and GH testing kit, and you have everything you need to start.  Long-lasting, as you can buy replacement bottles as your testing solution is finished, this is great as you only have to replace one once in a while.

Many reefers will not dedicate the time it takes to use this product. If this is you then buying it is not a good idea.  Be honest with yourself are you going to do this if not testing strips may be a better option for you. (4/5)

Red Sea Fish Pharm ARE21525 Marine Care Test Kit for Aquarium

Redsea Marine care test kit for saltwater aquarium tests for nitrate, nitrite, ammonia, pH, and alkalinity levels.  This test kit is better for saltwater aquariums that have delicate corals as the accuracy of these kits are superior.

The quality of the various elements and the storage solution will last you years.  Replacement solution bottles don’t come with all the other elements, and if one breaks, you will have to purchase the kit again.


  • Accuracy of the kit
  • Quality of the components
  • Replacement solutions


  • This test kit is on the pricey side

Our verdict:  This testing kit is fantastic for marine aquariums with delicate fish or if you want to grow corals.  Test kits are available in combinations or as separate units with refill solutions.  The storage solutions and all the elements are durable and will last for years.  The initial outlay may be costly but in the long run, may save you money (4 ½/5 stars).

Although, in the beginning, testing kits are fun to use after the novelty wears off, are you going to use it?  Besides, do you have that much time to dedicate to testing?  With multiple tanks and having to clean the vials with distilled water before you move on to the next tank (if you do not buy extra vials), it could take a better part of a day to complete all these tests.  There is a solution to test pH and as a standalone pH tester is possible but not ideal.

Testing strips

Testing strips will give you a large amount of information about the water quality of your tank, including a pH tester block.  If you only have to test your pH levels weekly, then this is a good option.  If you are testing your pH levels more often, a digital pH meter is better.

Tetra EasyStrips 6-in-1 Aquarium Test Strips

Tetra easy strips are easy to use, and after 10 seconds, you will have your results.  This test tests for nitrate, nitrites, hardness, chlorine, and pH.

Dip in the tank for 1 second and wait for another 10 before reading the results.  Holding the testing strip to the bottle is easier to match the colors of each of the elements.  It is accurate and easy to use.

To see this product in action, watch this YouTube video.


  • The time it takes to use the product
  • Convenient and easy to use


  • No ammonia test strip

Our Verdict:  Quick and easy to use for multiple tanks, strips are handy.  The speed of using strips beat solutions every time.  Tetra, as a brand for testing strips, is accurate enough to make solution testing obsolete.  Ammonia is dangerous to your fish, and a real-time ammonia monitoring tool will make the con mute.  (4/5)

JNW Direct 9 in 1 Aquarium Test Strips

The JNW 9 in 1 aquarium test strips test for total hardness, free chlorine, iron, copper, nitrite, nitrate, pH, total alkalinity, and KH easy to use with a dip into the aquarium and compare with the color chart on the bottle.

The interesting feature of this testing strip is you can record, track, and monitor the results using your smartphone (IOS and android).  This product is reasonably priced and can track your records over a period of time.

The app has an e-book that gives users information about the results of the test; this is great for a new hobbyist to use until you gain a better understanding of the parameters and the causes that change these levels.


  • The recording app for your phone
  • Readily available information for the results
  • Easy and quick to use


  • No ammonia testing

Our verdict:  With its ease of use and the electronic recording of the information are both great features.  This kit is a reliable product and overall gives useful information.  Ammonia testing will have to be done, but a real-time meter for ammonia is important and does not detract from this product.  (4 stars)

Testing strips are fairly accurate and have the same disadvantages as with solutions, where you have to determine the color before reading the level.  Before you decide between using testing strips and solution kits, its better for you to have a look at this video where both products are used.  As a standalone pH tester is not available this is not the best solution for pH testing.

Why Use A pH Meter and Not A pH Testing Strip?

The pH level of the water in your fish tank can change because of the nitrogen cycle and low KG levels of water.  The pH level of your fish tank is important for your fish if it is too high or too low; it may affect the health of your fish.  Corals are even more sensitive, and some fish will only breed if the pH levels are correct.  With weekly monitoring, you will be able to keep your environment stable.  This makes a pH tester an essential part of any testing kits for fish tanks.

The need for pH and temperature testing changes during the life span of your tank and may increase from weekly to daily and even several times a day.  In these circumstances, having a digital pH meter may make all the difference in the world.

pH testers have different pros and cons, depending on what you are using the tester for.  The pH of some fish needs to be precise, and you may have mixed species with a narrow window of compatibility when it comes to pH levels and may have to test more often.

When conducting pH testing, you want something that is both easy and convenient.  During your fish keeping, you may need to test pH daily, and to take out the solution kits and mixing them daily is going to get real old real fast.

The testing strips cannot be reused, and the cost could add up quickly if you need to test the water daily or even more than once a day if you are experiencing a problem.

The accuracy of the kits and the strips is variable, they depend on being able to distinguish colors that may be fairly similar, and this has been known to cause incorrect readings.

The digital pH meter is more accurate and easier to use. However, it may need to be calibrated first, and after that, it is simple to use. All you do is read the numbers off of a screen, and you can reuse it over and over again and record the data. Clean the digital pH Meter electrode probes with a specialized washer.

calibrating your digital pH meter

Most digital pH meters are calibrated in three easy steps:

Step #1: Clean the electrode probe with distilled water (you can use RODI Water) and allow to dry

Step #2:  Place the electrode probe into the buffering solution that is pH 7 and program the reader to 7

Step #3:  Repeat with a buffer solution with a pH level of 2

Your pH tester is ready to use.  Check the manufactures details as some machines need different steps.

You may have to recalibrate your meter, depending on your needs.  If you need a precise reading, then you need to do it every time you use it, but for most of us, weekly is fine.

You have to recalibrate your digital pH meter if you have not used it for some time or if you have tested a solution that has either high acidic or alkaline reading.

Using your digital pH meter with liquids

Step #1:  Rinse the electrode probe with distilled water

Step #2:  Rinse a container out with distilled water

Step #3:  Use the container to remove a sample of the substance you want to test. For an aquarium (liquid solution) take a sample from the middle of your tank

Step #4:  Turn on the meter and check that it is in pH mode

Step #5:  Place the electrode probe into the sample of the solution you want to test leave it for a moment

Step #6:  Take the reading on the display monitor

Step #7:  Rinse with distilled water and pack the pH tester away

Using your digital pH meter to test soil

The best garden pH meters is a digital pH meter.  The sample removed for the testing kit is less suitable than allowing the soil to change the pH of the distilled water over time as multiple samples need to be taken when conducting pH soil tests.

Step #1:  Rinse the electrode probe with distilled water

Step #2:  Dig a hole about 2 to 4 inches deep and fill with distilled water

Step #3:  Repeat step #2 in a few areas about 2 feet apart

Step #4:  Turn on the meter and check that it is in pH mode

Step #5:  Place the electrode probe into the first hole

Step #6:  Take the reading on the display monitor

Step #7:  Rinse with distilled water and move to the next hole and repeat the process

Step #8: Add all the pH levels and divide by the number of holes you made and that is the average pH level of the soil

Step #9: Rinse the pH tester with distilled water and pack it away

Factors to consider when choosing a pH meter

  • pH for
  • pH readings you need to take

The answers to these questions will determine which pH tester is the best one for you.

What do you need in a pH meter accuracy and sensitivity, and we all want value for money.  Digital pH meters are suitable as a soil and water pH tester.  For sensitive fish tanks and reefers who have changed an element, then testing strips and kits are better pH testers as it gives you more tests than just pH levels.

New reefers need both a digital pH meter for daily testing and either testing kits or strips can be used as pH testers weekly testing.

Types of Digital pH meters

  • pH pen tester that has the accuracy of the benchtop pH meters but is portable
  • pH meter that Bluetooths the information to an app on your phone that keeps the data stored

Where can you purchase a pH meter?  pH testers of every kind are readily available from pet stores, online stores, the local pool shop, and many hardware stores too.

Digital pH Meter

Digital pH meters are easy to use and give you accurate readings if you don’t need to know the other elements in your tank.  Digital pH meters are the best pH meters for soil testing and can be used to test pH levels in all liquids.  They are not only for your fish tank if you have a pond, pool, hydroponic, or aquaponics garden; this is the best pH tester for you.

KoolaMo Digital pH Meter Water Quality Tester

The KoolaMo Digital pH Meter has a built-in thermometer, and this pH tester will automatically compensate for the temperature of the substance when calculating the pH level. Whereas other meters may give inaccurate readings when you are testing. Affordable and is easy to read.

It comes with the two packets of powder to mix with distilled water to make the calibration solution.  Mix each one into airtight containers, and you can reuse it.


  • You can use it in multiple areas
  • Easy to calibrate
  • Temperature adjustment


  • This device only tests the pH level

Our verdict:  If you have an established tank and you understand the causes of the pH levels, then a temperature adjusting one step calibrating digital pH meter reader is the best option.  Many reefers don’t want to use distilled water to clean their meters.  Using tap water may leave a residue on the meter, causing false readings, but as all digital pH meters should be rinsed off with distilled water, this is not a problem specific to this device.  (4/5 stars).

This YouTube video shows you how to calibrate.

If hydroponic gardens interest you, adding a garden to your aquarium hobby will reduce water consumption and help clean your fish tank too.  Aquaponics Fish Tank – Take Your Hobby to the Next Level.

VIVOSUN pH and TDS Meter Combo

This meter is two separate devices one is a pH tester and the other test the TDS; if you need the readings of both as an intermediate reefer having both these readings has practical value to determine if you need to conduct further screening. Durable with its protective cover, quick and accurate.


  • It has the TDS and pH reader
  • Can be used for soil and water
  • The protective covering


  • The TDS Meter will have to be recalibrated after a year
  • The powder packets are small

Our verdict:  ThispH tester Not bad with its high level of accuracy, easy to read.  If your tank is in balance, knowing TDS changes is a good thing, and a meter reading is easier than strips. If you see a spike, you will know what to look for.  The TDS meter can be used to test your RODI water, and this is a plus.  (4 1/2 /5 stars).

Dr.meter 0.01 Resolution High Accuracy Pocket Size pH Meter

This test kit has a high accuracy level and heat adjustment, but a big problem is it cannot convert to degrees Fahrenheit.  This pH tester is a high-quality product, and how often do you get batteries included.


  • Easy to use once calibrated
  • High accuracy
  • Batteries included


  • The metric measuring units cannot be changed
  • Difficult to calibrate

Our verdict:  The factor of being unable to convert from the metric measuring unit for US shoppers will make this pH tester a non-starter.  Added to it, the difficulty of calibration may not be a good choice for others either. (3/5 stars).

PC60-Z Bluetooth Multi-Parameter Smart Tester Powered by ZenTest Mobile App

This digital pH meter gives you the best of the lab testing kit and mobile device.  The solution takes PH, TDS, Salinity and resistivity, and temperature.  In addition, this tester compensates for temperature.  The data can be sent via Bluetooth to an app downloadable to your smartphone.  This app allows you to record data and store it to monitor the changes automatically.


  • Bluetooth connection
  • App data tracking
  • Tests different elements


  • Losing data if the data has not been backed up to the cloud
  • The price

Our Verdict:  The automatic recording of data is a bonus.  The temperature and salinity testing information make this meter reader perfect for saltwater aquariums and useful for freshwater aquariums too.  This pH tester is possibly the best pH meter for hydroponics and aquaponics gardens too (Stars 4 ½/5 stars).

Bluelab PENpH pH Pen Fully Waterproof Pocket Tester

This pH pen is a high-quality product with automatic temperature compensation.  The pH pen has to be stored with a few drops of the storage solution.  Kits with solution powder are available can be replaced later with the premixed bottles that are less messy and easier to use.  You have to store it with the storage solution in the cap and top it up weekly.  The powder mix is not going to last for long.

Bluelab STSOL100 KCL Storage Solution

A bottle of the storage solution that you will purchase after your mix has been depleted.  This is used to keep the pH tester lubricated and in working condition.

Bluelab Calibration Solution

Bluelab pH pen calibration premixes available in different quantities that you can use to calibrate you pH tester after your packets have been completed.


  • Accurate
  • The premixed solution is convenient


  • The price

Our verdict:  This is a high-quality pH tester that comes with a 1-year warranty.  With the premixed solutions making it less messy to use.  The calibration marker is handy and tells you when you need to recalibrate this pH tester.  The features are nice, but the price is another matter.  If one compares it to the PC60-Z Bluetooth Multi-Parameter and having the Bluetooth recording information makes the price of this device hard to swallow (stars 3/5).

This YouTube video made by bluelab on bluelab pH pen calibration and storage.

FAQ’s on pH Testers

What Does A pH Tester Do? A pH tester measures the alkalinity and acidity of a solution.  Digital pH meter tests the hydrogen-ion levels of a solution and the voltage between two electrodes.  pH testers like strips and test kits read the acidity of a liquid using a chemical reaction that creates a color that indicates the pH of a solution.

How Often to Calibrate pH Meter? How often you need to calibrate a digital pH meter differs from the device and the accuracy you need. If you need pinpoint accuracy calibrating the meter before use is advisable for most brands.

Why is the pH Meter Most Accurate? pH testers either have a number displayed on the screen, or you have to match a color to a chart.  Matching colors is not as easy as it first appears, whereas reading numbers from a screen leaves little room for error in the interpretation of your data.  As long as your pH meter is calibrated, it will be easier to detect small changes to pH levels in your tank.

What is the Best Soil pH Tester? The best pH tester for soil is a digital pH meter.  Mix distilled water into a 2-inch hole and wait a few minutes before testing the pH level of the water.  Repeat this process in different locations to find an accurate reading.

How to Test Soil Ph With Ph Meter? How to use a pH meter for soil?  You need a digital pH tester and distilled water.  Dig a hole 2 inches in depth and fill with distilled water.  Move to different locations about 2 feet apart and repeat the process.  Use a digital meter to take a reading in the first hole and proceed through the patch of soil.  Add up all the different amounts and divide this number by the number of holes you have dug, and this will give you an average pH level for the soil.

How to Calibrate pH Meter Without Solution? Calibrating a pH tester without a solution is not recommended, but it is possible.  The accuracy will be affected by using this method.  Most digital pH meters need two calibration tests, pH 7, and pH 2.  Place the meter in distilled water and calibrate it to 7.  Squeeze the lemon and collect the juice and calibrate the pH tester to 2.  The problem with this method is that the pH levels in either can vary.  Distilled water contaminated with CO2 will raise it a little, and the pH levels of all food change depending on what water and food were administered during the growing phase.  These elevations are minor.

What pH Tester is the Right One

Finding the correct pH tester is tricky.  A digital pH meter is great if you only need to know the pH level in any given solution or soil.  If you need more information, a testing strip is better, and in the ideal world, having both handy will prevent you from needing something and not having it.

For marine aquariums growing corals or if you are planning to breed your fish, the testing solution kits are a better choice for weekly testing.  Keeping an eye on the pH levels more than once a week is better in this situation and pairing the kit with a digital pH meter, which will give you accurate information, multiple uses and is quicker to use.

Select fish that complement each other and where the pH margins are not too narrow, which will give you a tight window for error.  Whichever one or combination of pH testers you decide on is up to you, but all reefers agree that testing the water is vital to keep our fishy friends happy and healthy. 

Also read – How to Choose the Best Automatic Fish Feeder

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