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API GH & KH TEST KIT Freshwater Aquarium Water Test Kit, 2.5 oz.

4.7 4.7 out of 5 stars 5,072 ratings

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GH & KH

Purchase options and add-ons

  • Contains one (1) API GH & KH TEST KIT Freshwater Aquarium Water Test Kit, including 2 bottles of testing solution and 2 test tubes with cap
  • Helps monitor water quality and prevent invisible water problems that can be harmful to fish and plants and cause fish loss
  • Accurately measures GH & KH in freshwater aquariums
  • Water hardness is a measure of the dissolved mineral content of water and should match fish natural habitat to prevent fish stress and keep them healthy
  • Use for weekly monitoring and when water or fish problems appear

Customer ratings by feature

Instruction quality
5.0 5.0
Easy to use
4.2 4.2
Accuracy
4.2 4.2
Easy to read
4.1 4.1

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API GH & KH TEST KIT Freshwater Aquarium Water Test Kit, 2.5 oz.
API GH & KH TEST KIT Freshwater Aquarium Water Test Kit, 2.5 oz.
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Get it as soon as Sunday, Mar 24
Get it as soon as Sunday, Mar 24
Get it as soon as Sunday, Mar 24
Get it as soon as Sunday, Mar 24
Get it as soon as Sunday, Mar 24
Get it as soon as Sunday, Mar 24
Customer Ratings
Easy to use
4.2
5.0
4.5
4.6
Accuracy
4.2
4.8
4.5
4.4
Easy to read
4.1
5.0
4.5
4.6
Value for money
4.0
4.5
4.7
4.6
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From the manufacturer

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test

Testing the Waters

In order for fish to thrive, water must be similar to that which could be found in their natural environment. Poor water quality can cause fish stress, illness and even loss. Most common water quality parameters are Ammonia, Nitrite, Nitrate, and pH. All may vary over time and all are invisible to the eye which is why it is important to test weekly. Testing aquarium water weekly will aid in keeping your most important water parameters within the proper range for your aquarium. Choose from a wide range of API testing options, such as our popular FRESHWATER MASTER TEST KIT or 5-IN-1 TEST STRIPS, for accurate water evaluation. Regular testing will help you easily determine your aquarium conditions.

Find Your Ideal Testing Style!

Test

Test

Test

Test

Your API Test Options

Choose the test method that works best for you. Whether you’re a bit pressed for time, or you prefer to measure your parameters on a more in-depth scale, or you only need to test one or two specific parameters, API has what you need!

Dip and Read

Just dip a 5-in-1 TEST STRIP in your aquarium, swirl twice, and compare to our color chart for fast and accurate results.

The Scientific Approach

For more detailed analysis, use the FRESHWATER MASTER TEST KIT, POND MASTER TEST KIT, SALTWATER MASTER TEST KIT, or REEF MASTER TEST KIT for precise readings of parameters.

Pick One (or Two)

Need to check your phosphate levels? What about ammonia? API offers specific test kits to test many different parameters, from general hardness and copper to pH and nitrate. Grab the one you need for a streamlined approach to testing.

Test Test Test Test Test Test
API QUICK START API AMMO-LOCK API pH UP API pH DOWN API NITRA-ZORB API PHOS-ZORB
Customer Reviews
4.7 out of 5 stars
12,027
4.6 out of 5 stars
4,824
4.6 out of 5 stars
609
4.5 out of 5 stars
1,617
4.4 out of 5 stars
2,514
4.5 out of 5 stars
410
Too much nitrites?
Too much ammonia?
Inappropriate pH levels?
Too much nitrates?
Too much phosphates?
test

Making a Better Underwater World

At API, we understand the rewards and relaxation of fishkeeping because we have a passion for fish too. 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.

Product guides and documents

Product details

  • Is Discontinued By Manufacturer ‏ : ‎ No
  • Product Dimensions ‏ : ‎ 2.75 x 1.63 x 5.13 inches; 2.5 ounces
  • Item model number ‏ : ‎ 58
  • Department ‏ : ‎ Unisex-Adult
  • Date First Available ‏ : ‎ June 20, 2004
  • Manufacturer ‏ : ‎ Mars Fishcare
  • ASIN ‏ : ‎ B003SNCHMA
  • Country of Origin ‏ : ‎ USA
  • Customer Reviews:
    4.7 4.7 out of 5 stars 5,072 ratings

Looking for specific info?

Product Description

Keep your fish healthy and thriving by testing your aquarium water's GH levels regularly with this easy-to-use API GH & KH TEST KIT for freshwater aquariums. Testing water parameters weekly helps prevent invisible water problems that can be harmful to fish. Water hardness is a measure of the dissolved mineral content of water. There are two types: the general hardness (GH) and carbonate hardness (KH). When keeping freshwater fish and plants, the GH and the KH of aquarium water should match their natural habitat. The API GH & KH TEST KIT helps aquarists duplicate the natural habitat of their fish, as well as detect low KH levels, which can lead to rapid and wide pH shifts, stressing fish. API GH & KH TEST KIT contains KH test bottle, GH test bottle, instructions and two capped test tubes.

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.

Important information

Safety Information

Please Read Instructions Before Use

Directions

It is necessary to test the GH and KH to monitor water quality and prevent stressful conditions.

To report an issue with this product or seller, click here.

Customer reviews

4.7 out of 5 stars
4.7 out of 5
5,072 global ratings

Customers say

Customers like the value, ease of use, and quality of the pet supplies. They mention that it gives a very reasonable estimate to the true value of your water, and that the instructions were included. They are also happy with accuracy, and water quality. That said, some complain about the color. Opinions are mixed on durability.

AI-generated from the text of customer reviews

248 customers mention218 positive30 negative

Customers like the quality of the pet supplies. They say that the test works well, the results are easy to discern, and the test difference is definitely notable. They also say that it's a decent useful product and that the API liquid test kits are better than the strips.

"...I’m pleasantly surprised as it came in great condition and works wonderfully! Easy to measure gh and kh!..." Read more

"The API GH and KH Test Kit is fairly easy to use, and it is easy to determine the results, and the results seem accurate...." Read more

"This test works good once you're used to it. A single drop one with a color sheet might be easier to use, but this is more accurate...." Read more

"Work great" Read more

171 customers mention131 positive40 negative

Customers find the pet supplies easy to use. They mention that the API GH and KH Test Kit is fairly easy to learn, use, and understand. The bottles did not leak and instructions were included.

"...This product is very easy to use, even compared to the API freshwater test kit, which really should include GH and KH...." Read more

"The API GH and KH Test Kit is fairly easy to use, and it is easy to determine the results, and the results seem accurate...." Read more

"...The kit here is easy to use with well written instructions and everything you need to do the tests...." Read more

"The test kit is very easy to use. API makes top of the line test kits for aquariums. I pretty much buy exclusively from them for very good reason...." Read more

99 customers mention84 positive15 negative

Customers like the accuracy of the water hardness kit. They mention it's easy to use, provides accurate testing, and stays consistent. Some customers also mention that the kit is a great kit for testing general hardness and carbonated hardness.

"...Easy to measure gh and kh! I would buy again:) I also ordered the phosphate tester and that came in good condition too." Read more

"...easy to use, and it is easy to determine the results, and the results seem accurate. The API GH and KH Test Kit comes with 2 test tubes...." Read more

"...drop one with a color sheet might be easier to use, but this is more accurate...." Read more

"...Between the two, I feel confident that my PH readings are accurate...." Read more

53 customers mention39 positive14 negative

Customers like the value of the water quality test. They say that it is accurate at a good price, and it gives a very reasonable estimate to the true value of your water. Customers also mention that the test shows proper values when testing with tap, distilled, and ro water.

"...These are widely available and fairly inexpensive. They are not as easy to use as the test strips...." Read more

"Accurate at a good price. Keeping taps on the KH is very important if you want to keep your tank healthy, KH is much more important the PH...." Read more

"...sure if I left the cap open or unscrewed, but it seems like the bottle is useless...." Read more

"...and have always found them to be quick, easy, reliable, and reasonably priced...." Read more

25 customers mention20 positive5 negative

Customers like the water quality of the pet supplies. They say it works flawlessly, is a great way to test aquarium water parameters, and is essential for checking water conditions. The kit is also good for checking the water hardness and CO2 levels. Some say the liquid tests are the best and are a good tool for all aquarists.

"...kit has helped me monitor my CO2 levels as well as monitor my increases in water hardness...." Read more

"...It also has a handy legend listing which ranges are ideal for which types of fish...." Read more

"...Overall it’s a good product to determine aquarium parameters." Read more

"...As expected, the water in his tank was showing very, very soft...there were virtually no minerals in it...." Read more

40 customers mention17 positive23 negative

Customers are mixed about the durability of the pet supplies. Some mention that the bottles will last a long while, while others say that the glass vials break easily.

"...They break easily. At this point, I have more tests than glass vials...." Read more

"...Thankfully (and luckily, considering the packaging), the vials were not shattered...." Read more

"Received test kit, opened box, test tubes were broken." Read more

"The package came and they were double wrapped and nothing was broken. The bottles did not leak and instructions were included...." Read more

47 customers mention6 positive41 negative

Customers are dissatisfied with the color of the pet supplies. They mention that the colors had already changed before use, the color is faint at first, and there is no color card included. Customers also say that it's difficult to tell when the yellow turns green, and that the tests go from green to greener and are useless.

"...One complaint I see here is that the GH test was green from the get-to. I think that is because their water was just that soft...." Read more

"...However, there was no booklet, no color chart, only a sheet of microscopic instructions in like 17 languages...." Read more

"...would turn yellow as the instructions indicated but it turned a deep bright orange. It was definitely not a pale yellow!..." Read more

"...are confused when they don't see a color chart but there is no color chart in this kit. Read the instructions. It's simple...." Read more

Great product, but BEWARE AMAZON PACKAGING!
4 Stars
Great product, but BEWARE AMAZON PACKAGING!
The test kit is very easy to use. API makes top of the line test kits for aquariums. I pretty much buy exclusively from them for very good reason. To me the instructions were easy to follow but after glancing at other reviews I suppose they could be a bit more concise. Minus 1/2 star, rounds back up to five.However, this item was shipped in severely inadequate protective packaging, and arrived predictably and seriously damaged. This is the first time that I can recall having a problem with Amazon Fulfillment's packaging choices, but it was a serious issue in this case. I'm subtracting only another 1/2 star because that's the shipper's fault, not the manufacture's. So now we're down to the four. Details on the packaging are below in my complaint to Amazon:"This is a chemical test kit that includes liquid chemicals and fragile glass vials. The item arrived in soft envelope packaging and as such had been predictably crushed. One of the chemical bottles had been squeezed and leaked probably a months worth of test solution all over, staining the box and instructions. Thankfully (and luckily, considering the packaging), the vials were not shattered. The amount of test solution lost is not worth the hassle of returning in this case, but the fragile nature of this item along with liquid components really demands shipping in a BOX, not an envelope. Please note that the included pictures were taken after cleaning up the considerable mess all over the solution bottles and vials" inadequate
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Top reviews from the United States

Reviewed in the United States on December 17, 2023
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Reviewed in the United States on December 21, 2023
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Reviewed in the United States on August 9, 2020
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Reviewed in the United States on January 1, 2021
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Reviewed in the United States on June 17, 2022
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Reviewed in the United States on January 12, 2024
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Reviewed in the United States on October 17, 2023
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Reviewed in the United States on September 14, 2023
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Top reviews from other countries

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Kausik Das
5.0 out of 5 stars Nice test kit to test general hardness and carbonate hardness of the water.
Reviewed in India on February 13, 2022
Style: GH & KHVerified Purchase
2 people found this helpful
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Gery
5.0 out of 5 stars Genauer als der test von JBL!
Reviewed in Germany on October 31, 2019
Style: GH & KHVerified Purchase
Pietro A.
5.0 out of 5 stars Qualità alta prezzo basso
Reviewed in Italy on December 5, 2018
Style: GH & KHVerified Purchase
Derek Greenhalgh
5.0 out of 5 stars Muy necesario para cuidar bien peces y gambas en el acuario.
Reviewed in Spain on February 18, 2018
Style: GH & KHVerified Purchase
2 people found this helpful
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Aquarium stock
5.0 out of 5 stars Must have for dedicated aquarium hobbies
Reviewed in Japan on April 10, 2020
Style: GH & KHVerified Purchase