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API SALTWATER MASTER TEST KIT 550-Test Saltwater Aquarium Water Test Kit

  • Based on 39,125 reviews
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Availability: In Stock.
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Arrives Tuesday, Jun 9
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Style: Saltwater


Features

  • Contains one (1) API SALTWATER MASTER TEST KIT 550-Test Saltwater Aquarium Water Test Kit, including 6 bottles of testing solution, 1 color card and 4 test tubes with cap
  • Helps prevent invisible water problems that can be harmful to fish and cause fish loss
  • Accurately monitors 4 most vital water parameters levels in saltwater aquariums: high range pH, ammonia, nitrite and nitrate
  • Designed for use in saltwater aquariums
  • Use for weekly monitoring and when water or fish problems appear

Description

Protect marine fish and invertebrates from unsafe water conditions with API SALTWATER MASTER TEST KIT. Fish waste, uneaten food, plant refuse and other organic compounds can create harmful levels of ammonia, nitrite and nitrate as well as cause drastic fluctuations in pH. These unhealthy conditions can result in fish stress, gill and tissue damage and even death. The API SALTWATER MASTER TEST KIT accurately measures these four saltwater parameters that are key to keeping your aquarium healthy. It includes six bottles of liquid test reagent, four test tubes with snap-tight caps, a holding tray and a step-by-step instruction booklet with information on how to correct unsafe water conditions. Simply fill a clean test tube with 5 ml of water, add the appropriate test drops and compare results with the color chart. Then follow the recommendations to modify conditions if action is needed. With API aquarium products, it’s easy to keep a beautiful saltwater, freshwater or reef aquarium. For almost 60 years API has developed premium solutions with proven and effective results for your family and ours. API offers a range of testing kits, water conditioners, and nutritionally superior food, because we’re dedicated to making a better underwater world. They work to provide a safe, hospitable environment for fish such as tropical community fish, cichlids, goldfish and more. At API, we understand the rewards and relaxation of fishkeeping because we have a passion for fish too.

Is Discontinued By Manufacturer ‏ : ‎ Yes


Product Dimensions ‏ : ‎ 7 x 5.75 x 4.75 inches; 1 Pounds


Item model number ‏ : ‎ 401M


Department ‏ : ‎ Unisex-Adult


Date First Available ‏ : ‎ June 20, 2004


Manufacturer ‏ : ‎ Mars Fishcare


Best Sellers Rank: #932 in Pet Supplies (See Top 100 in Pet Supplies) #2 in Aquarium Test Kits


#2 in Aquarium Test Kits:


Customer Reviews: 4.6 4.6 out of 5 stars (4,645)


Item Weight: 1 pounds


Department: Unisex-Adult


Manufacturer: Mars Fishcare


Item model number: 401M


Date First Available: June 20, 2004


Item Package Dimensions L x W x H: 6.69 x 5.16 x 4.39 inches


Item Dimensions LxWxH: 7 x 5.75 x 4.75 inches


Item Weight: 1 Pounds


Brand Name: API


Target Audience Keyword: fish


Directions: Follow the instructional booklet directions for individual testing of each water parameter, and test weekly for best results.


Country of Origin: United States


Model Name: SALTWATER MASTER TEST KIT


Color: No Color


Size: 1-Pack


Material: Plastic


Number of Items: 1


Style: Saltwater


Included Components: API Saltwater Master Test Kit


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Tuesday, Jun 9

This item is non-returnable:

Non-returnable. Transportation of this item is subject to hazardous materials regulation

View our full returns policy here.

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Top Amazon Reviews


  • Work perfect
Style: Saltwater
Great test kit for my Helloreef salt water aquarium
Reviewed in the United States on February 5, 2026 by Daniel Robert

  • Relief to Use
Style: Saltwater
These are relatively easy to use and accurate. They are the same tests my LFS uses and my tank maintenance person uses. It is a great value for the money and a good accurate test kit for the average aquarium owner. My LFS still does testing once a month to ensure accuracy but this helps to catch anything going south with the tank in between maintenance visits. ... show more
Reviewed in the United States on October 20, 2024 by Bonnie Boe

  • Great product
Style: Saltwater
Greta testing kit. Shows all levels and very accurate.
Reviewed in the United States on March 31, 2026 by MJ

  • Good for the money, tells you where your water quality is.
Style: Saltwater
Work pretty well, not always the most accurate but if you know basically what you're looking for these work great. They don't always measure traces correctly, but traces don't mean much. Fast easy and gives you a good idea of tank water condition.
Reviewed in the United States on January 18, 2026 by Buick48

  • Worked
Style: Saltwater
Worked awesome
Reviewed in the United States on March 24, 2026 by Ashton Hubbard

  • A must have if you wanna keep fish water in the correct parameters
Style: Saltwater
Great tool to have on hand fresh water saltwater
Reviewed in the United States on March 23, 2026 by Michael G.

  • Perfect for cycling
Style: Saltwater
I didn’t want to buy expensive handheld testers for parameters I would only be consistently checking during cycling so this kit was perfect for that. Like any colorimetric test, reading the results introduces some error but that’s what you will get for most lower end test kits anyway. As far as accuracy I would say test strips < this test kit < handheld expensive test instruments android this is a good bang for your buck. The tests are easy to set up quickly, I wish I purchased this sooner! ... show more
Reviewed in the United States on March 2, 2024 by Emily

  • Good buy!
Style: Saltwater
This is a VERY easy testing kit. The chemicals that arrived had an expiration date of 2018 so ample time to use the product. Comes with 4 test tubes, easy color chart for reviewing test results, and a nice (but flimsy) storage box to store everything when it's done. The test instructions are the only thing I would change. The directions are simple enough, just they are in a booklet with several other languages made of plain paper. It works but I can see the book not lasting very long since these are water tests and accidents do happen. I already have a few wet fingerprints in it from getting the water out of my aquarium and browsing through the book. They should be laminated like the color charts, perhaps a card for each test. No big deal but certainly an improvement. I would recommend this to anyone though as it is a bargain and the test kit is great. ... show more
Reviewed in the United States on July 25, 2013 by Carolina Fiction Addict

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