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

  • Based on 4,697 reviews
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Availability: Only 4 left in stock, order soon!
Fulfilled by Kens Fish

Arrives Aug 29 – Sep 2
Order within 22 hours and 57 minutes
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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.

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: #3,468 in Pet Supplies (See Top 100 in Pet Supplies) #5 in Aquarium Test Kits


#5 in Aquarium Test Kits:


Customer Reviews: 4.6 4.6 out of 5 stars (4,697)


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 4.37 inches


Item Dimensions LxWxH: 7 x 5.75 x 4.75 inches


Item Weight: 16 ounces


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: Aug 29 – Sep 2

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

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

  • Tried and true even over Hannah
Style: Saltwater
I have all the Hannah checkers and guess what? I still revert back to the easy drop tests. Some of the Hannah checkers are cumbersome and it is easy to just fill the test tube and add applicable drops and shake. Hope they don’t stop making these test kits. Everything is included to use. Very efficient. ... show more
Reviewed in the United States on May 23, 2026 by Zena

  • 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

  • Cheap, Easy, and Good Enough
Style: Saltwater
The best part of this kit is the price. You get to test four test parameters for $15. Other brands will cost $20 for each test parameter. The tests are also highly standardized, requiring 5ML of tank water for each test, and often the same amount of drops from bottle 1 to bottle 2. Performing the tests seemed simpler and faster than other test kits I have tried, which includes Red Sea, Salifert, Elos kits. Accuracy is not quite as refined as other brands, but adequate enough for these basic parameters. Since ANY ammonia or nitrite is bad, I only really need to know if these parameters are not zero, and a basic sense that any water changes are having a beneficial effect. The nitrate color gradient could be a bit less subtle, but it is not useless. The plastic case is a bit flimsy but adequate, keeping the bottles and test tubes organized and held firmly. This is better than my Red Sea kit where the bottles and tubes are not held in place very well, or Salifert kits where everything is loose in a flimsy cardboard box. As another reviewer mentioned, the test tubes do leak if you shake them vigorously...so I resort to the wiggle method instead. ... show more
Reviewed in the United States on November 19, 2013 by skippy

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

  • Must have for success
Style: Saltwater
Can't run an aquarium ecosystem without this product! You have to know the quality of your water!
Reviewed in the United States on June 20, 2026 by kentrell white

  • 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

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

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