API Saltwater Aquarium Master Test Kit, 550 count

Rated 4.2941 out of 5 stars
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$35.98Chewy Price
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About This Item

  • Tests high range pH, ammonia, nitrite and nitrate levels to help keep your finned friend safe.
  • Designed to accurately measure these four saltwater parameters that are key to keeping your aquarium healthy.
  • Comes with 6 bottles of liquid test reagent, 4 glass test tubes with snap-tight caps, a holding tray and a step-by-step instruction booklet.
  • Easy to use—fill a clean test tube with 5 ml of water, add the appropriate test drops and compare results with the color chart.
  • This API test kit comes with over 550 tests so you can perform your routine aquarium maintenance.
Play Video: Learn More About API From Our Team of Experts
Learn More About API From Our Team of Experts

Help lower your aquarium's pH level with API's pH Down or raise it with API's pH Up water treatment.
Test your aquarium's water with API's replacement test tubes.

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.

Shop API

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Fish TypeMarine Fish, Marine InvertebrateMarine Fish, Marine InvertebrateMarine Fish, Marine InvertebrateTropical Freshwater, Marine FishTropical Freshwater, Marine Fish, Betta...
Aquarium TypeSaltwaterSaltwaterSaltwaterFreshwater, SaltwaterFreshwater, Saltwater

Questions & Answers

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ReviewsWrite a Review

Rated 4.2941 out of 5 stars
17 Reviews
Would recommend to a friend

17 Customer Reviews

Rated 1 out of 5 stars
By Fred on Dec 5, 2022

Not 550 tests in my kit

Ordered Oct. 12, 2022. Received within 3 days. By Dec. 5, 2022 nitrate solution was empty. Testing daily that's about 50 tests. Now I have to buy another test kit.

Rated 1 out of 5 stars
By John on Dec 19, 2020

API Amonia Test is bunk

Long after cycling my new saltwater aquarium I was getting .5ppm repeated readings over a period of several weeks well after into 3 months cycling a 75 gallon saltwater system with only 3 clownfish when using THIS test. So took a water sample to my local reef shop and found 0 ppm. So I googled this. Others had the same experience. This kits amonia test is bunk. Avoid!

Rated 5 out of 5 stars
By JIro on Nov 2, 2020

Good product!

Good product for testing parameters. Cost was a lot cheaper than in stores.

Rated 5 out of 5 stars
By Danny on Jul 24, 2020

Great value

Test. Was very accurate I saved 50% buy on chewy than from my local. Pet store

Rated 5 out of 5 stars
By Jacob on Oct 19, 2019

Perfect, Thank you!

Came Incredibly quick and secure. Cheapest you can find and it's exactly what I wanted. Thanks Chewy! You guys are the best around!

Rated 5 out of 5 stars
By alanjamesblair on May 19, 2019

Strong basic tests

For the nitrite cycle, these droppers are pretty good. The dip sticks are good for every couple of days, just to make sure nothing odd has happened, but for the serious tests, before adding a fish/invert or when you suspect something might be off, these droppers are a good test of the basic needs of your aquatic pals' water conditions. I recommend pairing it with other tests more specific to your sitch, such as the reef test kit for reefers, but for a good, strong, basic look at your cycle and pH+, this is a strong test kit.

Rated 5 out of 5 stars
By Tracey on Jun 2, 2019

So far so good

Same results at home as my 2 local fish stores got. Arrive fast, all bottles & glass intact. Very pleased with my purchase & service of Chewy

Rated 5 out of 5 stars
By Yaset403 on Jul 6, 2018

Great Test Kit

First of all, the shipping on my order was super fast. I needed the kit to test the water for amonia on my reef tank and received it super fast. The packaging was great. I have performed various test so far and I love this product.

Rated 4 out of 5 stars
By Bambam on Apr 29, 2018

Test good quality so-so

The test work well but the quality of the chemical bottles doesn’t seal well. If the lay in their side they leak. Upon arrival several had leaked everywhere. Cleaned them up and as long as they stay upright they are fine. The test tube don’t seal great so during test where you have to shake vigorously for one minute , it leaks some. Overall happy to have them!

Rated 4 out of 5 stars
By Photonut on Mar 16, 2018

Cheaper than strips!

It was like chemistry class. Little easier to read the strips. I bought both the reef and salt water fish test kits. The ph readings where the same!