Best Aquarium Water Test Kits*

These best-selling aquarium test kits were the most frequently bought by Petco’s pet parent customers and cover a wide range of testing needs for all types of aquariums and fish.


Pet parent faves

With saltwater and freshwater test kits, plus ammonia alerts, 5-in-1 kits, refractometers and CO2 indicators—this list of best-selling aquarium water test kits and tools is sure to help keep your aquarium clean, vibrant and thriving.

API Freshwater Master Test Kit


Freshwater Master Test Kit

This is one of the best freshwater test kits for comprehensive testing when setting up and maintaining your freshwater aquarium. The API Freshwater Master Test Kit includes a color range chart, glass test tubes and enough solution for over 800 tests. With this easy-to-use and accurate test kit, you can monitor your pH, high range pH, ammonia, nitrate and nitrite.

  • Designed for freshwater systems
  • Designed for fast, easy and accurate test solutions
  • Contains over 800 tests
  • Includes color wallchart, riveted color cards and glass test tubes
  • Made in the USA

Imagitarium Test Strips


Test Strips

These Quick-Test water test strips can be an easy and fast way to check your aquarium water for abnormalities outside the preferred water quality ranges. With Imagitarium Test Strips, you can quickly and accurately test your aquarium’s pH, alkalinity, hardness, nitrite and nitrate after a quick dip and compare results to the test results color chart that’s included. Help keep your aquatic environment an ideal oasis for its inhabitants with regular testing.

  • Designed for freshwater systems
  • Designed to be a fast, highly accurate testing method
  • Includes accurate, easy-to-read charts
  • 5-in-1 kit tests for pH, alkalinity, hardness, nitrite and nitrate

API Saltwater Master Test Kit


Saltwater Master Test Kit

This is one of the best saltwater test kits to help you maintain the correct water parameters that are vitally important to exotic aquatic life’s well-being in a marine enclosure. Let the API Saltwater Master Test kit help you verify your water quality is within the preferred ranges with over 550 tests for routine water checks. This economic test kit is designed to be highly accurate and easy to follow. The kit includes testing solution and test tubes for high pH, ammonia, nitrite and nitrate, along with an instruction booklet and color chart.

  • Designed for saltwater systems
  • Tests high range pH, ammonia, nitrite and nitrate
  • Includes all tests required to test the nitrogen
  • Consists of 6 bottles of liquid test reagent, a computer-calibrated laminated color card, 4 glass test tubes with snap-tight caps and a holding tray
  • Includes instruction booklet on how to correct unsafe water conditions

Seachem Combo Alert Pack 1 Year


Combo Alert Pack 1 Year

One of our best-selling continuous pH and ammonia aquarium water alerts, this sensor removes the need for regular testing of ammonia and pH. It provides a constant reading in your aquarium—which can be incredibly useful for sensitive species. Secure this sensor in a visible location in your aquarium, and you can easily check for any color change alerts whenever you want. This sensor is sensitive enough to pick up minor changes and can alert you if your aquarium needs attention before any signs of stress are displayed by your aquatic life. While the pH alert should only be used in freshwater habitats, the ammonia alert can be used in freshwater or saltwater aquariums, and both are made to last up to 1 year.

  • Designed for marine saltwater or freshwater use
  • Continuously detects and monitors ammonia and freshwater pH
  • No tests, no strips
  • Innovative ammonia alert color device using Seachem sensor technology
  • Sensor changes color from yellow to green to blue relative to ammonia concentration
  • Sensor can detect even less than 0.05mg (ppm) free ammonia
  • Innovative pH alert designed for use in the aquarium or filter and continuously monitors pH
  • Shows change in pH levels between 5.4 and 8.0.
  • Designed to last for over a year

Seachem Ammonia Alert Accessory


Ammonia Alert Accessory

Ammonia can quickly become harmful to even hardy fish species. In the early stages, detecting it is key to removing this chemical before it causes stress in your aquatic species. One of the best continuous aquarium water test alerts, Seachem’s Ammonia Alert Sensor is placed in your aquarium where it will provide constant readings of any ammonia concentration so that you can immediately address it before it reaches toxic levels. The sensor can last over a year in freshwater or saltwater aquariums and removes the need for regular testing of ammonia with strips or solutions.

  • Designed for marine or freshwater use
  • Unique hydrophobic sensor technology
  • Provides continuous readings
  • Designed to last for up to a year
  • Small, clear and unobtrusive
  • Color device continuously detects and monitors free ammonia
  • Sensor can detect less than 0.05mg (ppm) free ammonia and alerts you

Fluval Mini Master Test Kit


Mini Master Test Kit

This is one of the best miniature aquarium test kits. The Fluval Mini Master Test Kit can be an excellent tool for measuring the water parameters of your home aquarium. This kit has testing materials for pH, ammonia, nitrite, and nitrate—all of which must be within specific parameters for an optimal aquatic habitat. This kit is designed to be quick and accurate and can be used for freshwater or saltwater aquariums..

  • Designed for saltwater or freshwater systems
  • Includes essential testing of pH, ammonia, nitrite and nitrate to help maintain a balanced and optimal environment for your fish and plant life

API 5-in-1 Test Strips Freshwater and Saltwater Aquarium Test Strips


5-in-1 Test Strips Freshwater and Saltwater Aquarium Test Strips

These 5-in-1API aquarium test strips are designed to be a quick, accurate and easy way to evaluate water parameters. They measure nitrite, nitrate, carbonate, general hardness and pH of your aquarium water. Dip the strip in the water and compare it to the color chart provided to obtain your current aquarium parameters and discover what needs to be adjusted for the well-being of your pets.

  • Designed for saltwater or freshwater systems
  • Measures levels of nitrite, nitrate, carbonate, general hardness and pH
  • Helps prevent invisible water problems that may be harmful to fish
  • Made in the USA

Imagitarium Aquatic Refractometer


Aquatic Refractometer

A saltwater aquarium can add a lot of beauty and tranquility to your home. Having the proper salinity is often vital to the health and wellness of your aquatic life. The Imagitarium Aquatic Refractometer can help monitor your aquarium’s specific gravity so that you can maintain optimal levels and avoid drastic fluctuations—which can negatively affect your fish. This kit comes with a refractometer that measures specific gravity at parts per thousand and includes automatic temperature compensation, a dropper, calibration screwdriver, cleaning cloth, easy-to-follow instructions and a storage case.

  • Designed for saltwater systems
  • Measures on specific gravity and parts per thousand scales
  • Features automatic temperature compensation
  • Includes refractometer, dropper, calibration screwdriver, cleaning cloth and instructions

API Freshwater/Saltwater Ammonia Test Kit


Freshwater/Saltwater Ammonia Test Kit

One of the best ammonia aquarium test kits around is the API Ammonia Test Kit. It includes two dropper bottles, test solutions, easy-to-read instructions, test tubes, a results color chart and enough solution to run over 130 tests on your freshwater or saltwater aquarium. It can detect trace amounts of toxic ammonia in your aquarium, providing enough warning time to take action. While ammonia is a natural by-product in the aquarium, it can cause illness and even death to your aquatic inhabitants if it reaches certain levels.

  • Designed for saltwater or freshwater systems
  • Designed to be fast, accurate and easy to use
  • Contains two dropper bottles, test solutions, instructions, color chart and glass tube with a lid
  • For 130 tests for ammonia levels from 0 to 8 ppm
  • Made in the USA

Fluval CO2 Indicator Kit


CO2 Indicator Kit

One of our best-selling CO2 aquarium water indicators, the Fluval CO2 indicator is designed for use with the Fluval Pressurized CO2 System. It can help monitor and gauge approximate CO2 levels in your aquarium. CO2 is an essential element for photosynthesis in a planted aquarium. If you’re enjoying the beauty of a planted enclosure, monitoring CO2 levels is vital to the health of plants. The kit includes a 10mL CO2 indicator liquid, a CO2 indicator and a color-check decal to help you keep an eye on your natural aquarium’s CO2 levels.

  • Designed for saltwater or freshwater systems
  • Designed for use with Fluval Pressurized CO2 System, 88g
  • Indicates approximate CO2 levels in aquarium water to guide bubble dosing rate
  • Includes 10ml CO2 indicator liquid, CO2 indicator and color-check decal

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Learn More About Aquarium Water Test Kits

When used correctly, aquarium test kits can be very accurate. Fish water test kits are designed to be easy for users to compare to color charts to find their readings.

Your aquarium water test results can often depend on what kind of habitat and fish you have.

For freshwater aquarium water testing, you’ll want to regularly test for a few parameters—including water temperature, pH, ammonia, nitrite, nitrate and hardness.

Significant changes in water temperature can harm your aquatic life, so never place your aquarium near a window with direct sunlight or next to heating or air vents. Freshwater fish need a consistent water temperature of 72- to 82-degrees Fahrenheit. Aquarium heaters, chillers and thermometers can help you maintain ideal temperatures.

The pH scale ranges between 1 and 14, where 7 is neutral, below 7 is more acidic and above 7 is more alkaline. Freshwater fish typically do well with pH levels between 6.8 and 8.0, depending on the species of fish you have. A change in pH greater than 0.3 in 24 hours can leave fish stressed or susceptible to disease.

Ammonia is produced when waste, uneaten food and organic matter break down, which is very toxic to fish. It’s converted into nitrite by nitrogen-fixing Nitrosomonas bacteria.

Nitrite is also very toxic to aquatic life. Nitrite is converted into nitrate by Nitrobacter bacteria. Nitrate is relatively harmless to fish unless it’s in high concentrations. Plants use nitrates as fertilizer and complete the cycle by releasing oxygen into your aquarium water. Nitrate levels can usually be controlled with regular water changes. Most freshwater fish require readings to be 0 ppm ammonia and nitrite and less than 20 ppm nitrate.

Water hardness measures dissolved minerals in your aquarium water. Hard water has high levels of dissolved minerals and is usually high in pH, where pH tends to be more stable. Soft water has low levels of dissolved minerals and is generally lower in pH, and pH levels can change rapidly.

Brackish and saltwater systems need to be tested for specific gravity levels in addition to the other parameters.

Whether you have freshwater or saltwater fish, each fish species will have specific ranges for the ideal water parameters. For example, the desired parameters for Betta Fish are between 75- and 81-degrees Fahrenheit water temperature, 3 to 4 general hardness, 3 to 5 carbonate hardness and 6.5 to 7.5 pH levels. For Angelfish, ideal parameters are between 78- and 84-degree Fahrenheit water temperature, 3 to 4 general hardness, 3 to 8 carbonate hardness and 6.8 to 7.8 pH levels. Be sure to find out the exact aquarium water care required for your fish species and choose other species for your habitat with this in mind.

Aquarium salt and minerals—along with pH treatments and algae control solutions—can help keep your aquatic habitat in good condition. Water conditioners and filters will also be essential in helping you set suitable parameters for your aquarium.

*Based on sales data.