API Freshwater Aquarium Master Test Kit, 800 count

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About This Item

Details

  • Specifically designed to measure, modify and balance the conditions of freshwater aquariums.
  • Measures freshwater pH, high range pH ammonia, nitrate and water hardness.
  • Includes 4 test tubes, a holding tray for testing bottles and a test tube rack.
  • Helps protect your finned friends from toxic water conditions.
  • Easy-to-follow instructions, simply compare your results to the color card.

Instructions

FAQ

Learn More About API From Our Team of Experts

About API Testing

Testing the Waters

For fish to thrive, their aquarium water must be similar to the water in their natural environment. Poor water quality can cause stress, illness and even the loss of your fish. Important water quality parameters include ammonia, nitrite, nitrate, and pH. These can vary over time, and they are invisible to the eye, which is why it is necessary to test weekly. Choose from a wide range of API testing options like the Freshwater Master Test Kit or 5-in-1 Test Strips to accurately evaluate your water.

Pressed for Time? Just Dip and Read

Simply dip an API test strip into your aquarium, swirl it twice, and then use the color-coded chart to determine if your water is within safe parameters or if adjustments are needed. That’s it! API test strips are available in a 5-in-1 version, which includes testing for pH, nitrite, nitrate, carbonate, and general hardness. Ammonia and pH test strips are also available so you can mix and match according to your needs.

The Scientific Approach

Get professional results from the comfort of your home with API test kits. Measure up to six parameters with API Master Test Kits, or pick and choose from a wide variety of individual test kits. Both types of kits come with test tubes and a laminated, calibrated color card. API test kits allow for numerous tests, making them an inexpensive way to help keep your aquarium water quality in check.

How to Correct Aquarium Water Parameters

Too Much Ammonia?

Ammonia is released into the water through gills, urine, uneaten food and more. API Ammo-Lock detoxifies it instantly.

Inappropriate pH Levels?

Fish require a specific pH level to thrive. Use API pH Down to lower freshwater aquarium water pH to the right level.

Too Much Nitrite?

Use API Quick Start to quickly consume nitrite and help maintain an active biological filter.

Nitrates Too High?

API Nitra-Zorb helps remove nitrate and other toxins that can be harmful to fish and lead to algae growth.

About API

The team at API has a passion for fish and understands the rewards and relaxation fishkeeping can bring. For almost 60 years, they have developed premium products with a focus on proven and effective results. API offers a range of testing kits, water conditioners and nutritionally superior fish foods. They are dedicated to making a better underwater world for the benefit of fish and those who keep them.

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Questions & Answers

15 Customer Questions


Does this kit give us what is needed to correct the problem it discovers or do we purchase that separately?

Answer by ChewyNov 04, 2018
This kit is specifically designed to measure, modify and balance the conditions of freshwater aquariums.

How many water tests can you get out of one kit?

Answer by ChewyMar 10, 2024
This kit provides over 800 tests.

What's the difference between "fresh water pH", and "high range pH"?

Answer by ChewyJun 19, 2019
The pH Test will be able to read a pH level between 6.0 to 7.6. When keeping livebearers, goldfish, African Cichlids or marine fish & invertebrates, the High Range pH Test should be used. High Range pH Test will be able to read a pH level between 7.4 to 8.8.

How often should you test the water?

Answer by ChewyMar 10, 2018
As a rule of thumb, an established tank should be tested once a month, and any time there is a fish death or illness.

4.7
Rated 4.7 out of 5 stars
320 Ratings

186 Customer Reviews



Rated 1 out of 5 stars
By Jake on Jan 18, 2026

dont waste your money

have ran 4 different tests now all about a week apart. the water has never changed. always the same. never changes a color other than the drops you put in. dont

have ran 4 different tests now all about a week apart. the water has never changed. always the same. never changes a color other than the drops you put in. dont waste your money because it doesnt tell you anything.


Rated 3 out of 5 stars
By Scherry on Oct 21, 2025

it's a handy LITTLE kit for a beginner.

I ordered this kit mostly for it's size and the container. I thought once it was used up I could reuse the bucket to put my other test kits in but because of the

I ordered this kit mostly for it's size and the container. I thought once it was used up I could reuse the bucket to put my other test kits in but because of the way it's built (rather stupidly in my opinion) I can't do that so it will go into the landfill to add more pollution to the planet. The kit itself works fine but I gave it 3 stars due to the bucket. Ps, They won't let me load a picture of the inside of the bucket so you can see for yourself what in talking about!! If you look very close at the bottom of the picture you can kind of see. These companies need to start thinking about the recycling aspect of their products!


Rated 5 out of 5 stars
By Daniel on Dec 15, 2025

Simple

Pretty simple and accurate. Best way to check your tank health other than running to the pet store for a water reading. I trust these over the strips but everyone

Pretty simple and accurate. Best way to check your tank health other than running to the pet store for a water reading. I trust these over the strips but everyone has their preferences


Rated 3 out of 5 stars
By Jim on Dec 13, 2025

I received a used test kit!

The box was wet inside along with aquarium gravel in the bottom of the box. Instructions ruined and stuck together. Replacement item is on the way.

The box was wet inside along with aquarium gravel in the bottom of the box. Instructions ruined and stuck together. Replacement item is on the way.


Rated 5 out of 5 stars
By Kelsie on Dec 21, 2025

Test kit

This has help us get our aquarium parameters right for our fish and neocardina shrimp. Highly recommend

This has help us get our aquarium parameters right for our fish and neocardina shrimp. Highly recommend


Rated 1 out of 5 stars
By Ken on Jul 19, 2025

Arrived broken due to slight packaging error

I ordered this with 2 cases of dog food. For padding, they used 2 of those 1" thick cardboard pieces... NEXT to it! it was not put between the cans & the kit, it

I ordered this with 2 cases of dog food. For padding, they used 2 of those 1" thick cardboard pieces... NEXT to it! it was not put between the cans & the kit, it was NEXT to it in the corner of the box. This might have actually worked to keep the cans from crushing the kit, but the problem is, they were an inch shorter than the plastic tub was wide. There was absolutely nothing to prevent the cans from being slammed into the plastic. It's very sturdy plastic, this is NOT manufacturer error. The thin glass tubes also got broken, obviously. I appreciate chewy's QUICK shipping but maybe they should prioritize SENSIBLE PACKING too...


Rated 5 out of 5 stars
By Melissa on Nov 12, 2025

Accurate results

This is easy to use and seems accurate. The tank is established so I mostly just use the pH and nitrate

This is easy to use and seems accurate. The tank is established so I mostly just use the pH and nitrate


Rated 5 out of 5 stars
By Emily on Sep 5, 2025

Better Than Ever!

I needed to replace my old master kit when I started a new tank with a fresh cycle. It's the best there is, and now the test tubes are plastic instead of glass!

I needed to replace my old master kit when I started a new tank with a fresh cycle. It's the best there is, and now the test tubes are plastic instead of glass!


Rated 5 out of 5 stars
By Bill on Sep 6, 2025

The Gold Standard of Test kits

This is the only test kit that I trust, and now the test tubes are plastic instead of glass so they’re safer. Great price compared to big box stores.

This is the only test kit that I trust, and now the test tubes are plastic instead of glass so they’re safer. Great price compared to big box stores.


Rated 5 out of 5 stars
By Linda on Oct 7, 2025

Accuracy

Very easy to use, meaning reading the test results. I will definitely order this kit again.

Very easy to use, meaning reading the test results. I will definitely order this kit again.