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

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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


Manufacturer recommended age ‏ : ‎ 1 month and up


Item model number ‏ : ‎ 401M


Department ‏ : ‎ Unisex-Adult


Date First Available ‏ : ‎ June 20, 2004


Manufacturer ‏ : ‎ Mars Fishcare


Best Sellers Rank: #1,865 in Pet Supplies (See Top 100 in Pet Supplies) #2 in Aquarium Test Kits


#2 in Aquarium Test Kits:


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 4.4 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: Sunday, Nov 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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Similar Products

Top Amazon Reviews

    • A fish lovers must!
Style: Freshwater
This test kit has been a game changer for my freshwater tank. It includes everything I need to monitor ammonia, nitrite, nitrate, and pH levels. The instructions are clear and the color chart is easy to read, even for beginners. It works well and will keep your fish safe for any size tank :) I test weekly, and this kit has helped me stay ahead of any water quality issues. It’s lasted a long time and the case keeps everything organized. If you’re serious about fishkeeping, this kit is an absolute must. Although it can get pricey, it’s extremely worth the value! ... show more
Reviewed in the United States on August 2, 2025 by H. Lincoln
    • A Must Have Test Kit For Every Level Of Hobbyist
Style: Freshwater
API is a giant among companies that provide aquarium related products.They have maintained their sound reputation by offering innovative products and resisting the temptation to tamper with those which are already established and are time proven, dependable performers.The Fresh Water Master Test Kit belongs in the arsenal of tank maintenance and care products for every level of hobbyist from beginner to advanced. It's important to understand that these kits provide an indication only - it's unrealistic to expect a pin point reading as the tests aren't intended nor made to deliver that. But rather, to enable you to get a decent reading of say, where your PH level is knowing the accuracy may be off a few points sure beats shelling out $200 for a good digital PH meter.It's critical to understand these limitations and that they apply to everyone of the four included tests. PH High Range PH Ammonia Nitrites Nitrates For must of us, Ammonia is the most important because it's the number one killer of aquarium kept fish. The others are important of course, but Ammonia levels should always be checked and checked often. It's also important to pay attention to the expiration dates of the liquid reagents. Expired reagents mean off the charts inaccurate readings. Along with the liquid reagents the kit includes, instructions both in a small manual and attached to each bottle of testing liquid, four test tube, four plastic caps and a color chart. To ensure you get the most accurate reading possible compare the finished result to the card color block in the best possible light and against the most pure white background you can find. Just like computer monitors many of us see color differently which is the inherent draw back of this type of testing. But again, there is nothing else on the market at this kind of price point which can give you enough information to correct and adjust your key water parameters. If you're just starting out in this wonderful hobby, you'll master using this kit in no time and it will help you maintain a healthy and flourishing aquarium. Remember to never, ever rinse even cleaned test tubes in your tank water - even very small traces of testing reagents can be lethal to your fish. Draw water from your tank using a large plastic syringe available at any drug store, super market, or add one to cart from Amazon. For a full range of tests that cover the four most significant parameters you need to stay on top of - you can't beat the API Master test kits, not at this price. You can also buy replacement API test tubes which are sold in boxes of a dozen or 24 at a reasonable price, and a steal at Amazon. ... show more
Reviewed in the United States on April 1, 2012 by Peter Suslock
    • Great value
Style: Freshwater
Better than strips
Reviewed in the United States on September 30, 2025 by Photoman
    • accurate and easy to use, but buy with syringe/pipette
Style: Freshwater
easy to use and accurate. it's a bit expensive up front, but i'd say it's cheaper and more valuable in the long run because of the accuracy and amount of uses compared to disposable strips. the only comment/recommendation i have is to also buy a pipette or syringe with this to fill the 5 mL tubes for accuracy and convenience. i'd say this is a must have if you value your aquarium's well being ... show more
Reviewed in the United States on July 27, 2025 by mac
    • Easier than high school chemistry, but similar lab rules apply
Style: Freshwater
Have you passed high school chemistry? (And by pass, I mean be able to follow the rules while in a lab?) Then great! You'll have no problem using this test kit! However, be aware the instructions are like stupid tiny. I'm only 20 and even with reading glasses on top of my regular glasses these instructions are tiny. API offers a .pdf version of the instructions on their website, so I recommend those more than the little booklet. I also recommend one of those little syringes for like pet medication or human medication. It makes getting the water in the tubes a lot easier and with good accuracy. A lot of reviews mention the test tube caps not being tight when capped. I haven't had this problem, but also when I invert the tubes, I hold my finger on the cap and at the bottom of the test tube. This was a habit I picked up in college chemistry because sometimes it better to be safe than sorry. Gloves aren't necessary, but if you feel safer (especially since some of the chemicals are corrosive) then ball out with gloves! A lot of reviews also mention the nitrate test. I'm not a biologist, so I can't say the accuracy, however, make sure you read the instructions REALLY good as it's completely different than the others. You add 10 drops of solution bottle 1, shake the tube, shake solution bottle 2 for 30 seconds, add 10 drops, shake the tube for a minute, then wait the 5 minutes to develop. My few complaints is why I'm giving this a 4/5 stars because I feel like they really hinder the product. There's simply not an appropriate number of tubes. There's 5 tests, but only 4 tubes. Beyond that, they should really have 6 tubes since accidents are super prone to happen with tiny test tubes like this. Even beyond this, I feel a silicone or even plastic caps that screw with a rubber seal would be icing on the cake to eliminate the leaking and hardening issue. I'm also not buying API's 24 kit of tubes for a few extra tubes, that's just ridiculous. My next complaint is I believe they should add the GH and KH test in with this kit. pH, GH, and KH are usually all related to each other, so having that in the kit rather than paying $10 separately for it. I'd rather get it with the kit and pay 5-7 dollars more for the kit. To feed off some other reviews, adding the syringe like I mentioned would be better too since a lot of people probably won't think about it. Finally, I think a chlorine test would be great since it's toxic to most fish. However, I do believe in giving credit where credit is due and this kit is affordable which is great for those just starting to get into the hobby! I think the hobby is gate-kept by super expensive products, so having something like this that isn't $50+ is really helpful for those just starting out! I also love the size of this kit, it's easy to store. No test kit will probably ever be 100% accurate nor will they probably ever match up, but I feel this is good for America's market. I say that because I've used Sera, which is imported from Germany, and it's super nice with detailed and intense instructions which makes the tests feel a bit more accurate than this high school chemistry project. (Sorry API). However, the $80 keeps me from repurchasing and instead, buy this one. So, I guess that's the magic of capitalism and having other bills to pay rather than spending $80+ on a water testing kit. Even after being in the hobby since I was in middle school, I feel a lot of the prices in this hobby prevent people from advancing further and wanting to get into saltwater, reefs, or ponds. I stick with freshwater simply because it's the cheapest and easiest. Overall, recommend. 7/10, just be aware and take some of the recommendations some reviewers have already said and it should be smooth sailing. ... show more
Reviewed in the United States on August 22, 2021 by Hayley

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