API Reef Aquarium Master Test Kit, 1 count

Rated 4.6667 out of 5 stars
$34.98Chewy Price
$48.98Chewy Price
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About This Item


  • Measures calcium, carbonate hardness, phosphate and nitrate.
  • Comes with 4 different tests calibrated specifically for reef aquariums, 4 test tubes, a tray and easy-to-read color card for clear results.
  • Helps protect reef dwellers from dangerous water conditions.
  • High nitrate levels from fish waste and organic compounds can cause fish disease and algae blooms.
  • Easy to use—fill the test tubes, add the test drops and compare results to the color card.

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Play Video: Learn More About API From Our Team of Experts
Learn More About API From Our Team of Experts

Help keep your aquarium in tip-top shape with API's filtration pouches like Nitra-Zorb and Phos-Zorb.
Test your aquarium's water with API's replacement test tubes.

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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

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ReviewsWrite a Review

Rated 4.6667 out of 5 stars
12 Ratings
Would recommend to a friend

12 Customer Reviews

Rated 4 out of 5 stars
By corey on Oct 12, 2021

Good but missing magnesium

I love api test kits and I bought this one for my reef tank. Didnt realize it didn’t test for magnesium and I’m a little disappointed because now I must purchase a separate test.

Rated 5 out of 5 stars
By Cole on Jan 22, 2021

Works Perfectly

Did the job! Fish are happy and healthy. Check it often and hasn’t let me down

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

Accurate, according to my LFS

So I have my water tested by the LFS pretty much every time I go there, and unless I get the not so great person (1/8) I ask them to test with the stick and the drops. Every time I've done this, their readings are completely consistent with mine using this test kit. And I haven't noticed any problems that might indicate that the test kit AND their two are not working. So I plan to reorder this when I'm out. I will say that the kH and the calcium hardness are finicky, which means that you have to shake the vials after EVERY DROP! Do NOT get lazy and do a few drops at a time or you'll be out a test.

Rated 5 out of 5 stars
By Ivy on Feb 27, 2019

Came quick

My local petstore does not sell the reef kit, and charges about 15 more for their master test kits. This arrived quick and was a great price compared to other retailers. I still need some tests that this did not come with, such as magnesium and alkalinity, but at least I have most tests now.

Rated 5 out of 5 stars
By Kimberly on Dec 16, 2018

Fast delivery and just what I needed

I recommend this item to anyone that is in need to check on their aquarium water :) I was worried that my water levels were not right and item wasn't going to get here in time BUT it was a very fast delivery!

Rated 3 out of 5 stars
By MarineHobbyists956 on Sep 13, 2018

Great, but is missing elements

I use this product and its fantastic. It is missing yo test out magnesium. And thats a big part of growing ur corals nice and healthy.

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

Easy to read

I bought both test kits because we have fish and soft coral.

Rated 5 out of 5 stars
By BJDS on Feb 7, 2018

Marine tank

Test kit works great and easy to follow. I checked my water before going to aquarium store and my results matched theirs

Rated 5 out of 5 stars
By ballen13 on Oct 8, 2017
Top 1000 Contibutor

Reef testing made easy

Found the tests easy to use and helps keep track of the water conditions in my marine tank, it looked like a chemistry set when I first received it but it wasn't difficult at all, even for the beginners.

Rated 4 out of 5 stars
By Mike on Sep 26, 2017

Good starter test kit.

Not as accurate as a Salifert test kit but it will get you in the ballpark.