I received this from Amazon in August 2017. It always showed really high Nitrates no matter what. I cross referenced the results with several test strips (including 3 different brands at once) and they said my Nitrates were 10-20 ppm. I bought a new Nitrate kit from a big box store, and it confirms that my previous test kit (from Amazon) is way off.

I checked the date on the box and it is 10-2021, problem is the actual bottles say a different date (kind of weird in my opinion). Either way, I am disappointed. I spent a lot of time, and some $$$ reducing Nitrates for no reason Some items seem like they just shouldn't be purchased from Amazon.

On a side note; if your Nitrates are in the 40ppm + range, it is hard to tell what color the test is because the results colors are all shades of dark red.

Initial review: After following the instructions very specifically, I was unable to get a reading of copper after I dosed Cupramine into my 10 gallon quarantine saltwater tank. However, after letting the test tube sit for a day, I was able to get a copper reading. Read below for the full review and results:

EDIT: After letting the test tube sit for an entire day, I can actually distinguish a copper reading that seems to be nearly accurate with the amount of Cupramine I dosed. I tested ANOTHER sample of the same water, and got copper color immediately? Both tests look identical and it is actually reading right about 0.5mg/L. I am not sure if I should trust the readings, although they would be spot on with the amount of Cupramine I dosed. I'll test it with a Seachem test kit tommorow and update this review. Also make sure to follow the directions precisely, you need to remove the cap and look down the test tube with the white background of the color under the tube, but don't let the tube sit directly on top of the card, the color will appear much darker. Hold the test tube above the card an inch or two.

EDIT #2 02/19/18: The Seachem Copper Test kit arrived and the results are in: 0.5mg/L. Right at the amount I dosed. Tested again today with also the API Copper Test kit. Results again, are the exact same. 0.5mg/L. This means (in my case) both the API Copper Test Kit and the Seachem Test Kit are both precise measuring tools if you are dosing Cupramine.

I found that, at least for freshwater setups, the API test kit is as good as it gets without paying over $100 for sophisticated testing equipment ...which is completely unnecessary for our purposes. Using calibration solutions to verify color accuracy, I found the API test to read 1 ppm, 5 ppm and 10 ppm levels accurately. I also found API's color comparison method easier to read than other test kits, such as the [supposedly] more reliable Salifert kit. You can make your own phosphate calibration solutions - directions can be found at ThePlantedTank website.

The API test instructions - up to the point where you read the results - are clear enough. However, they don't tell you the best way to read the colors, which is the most important part of determining your phosphate levels, and this method goes for any such color-reading tests. DON'T lay the test tube against the color chart to compare the colors. Doing so will give you false readings (makes them darker). Instead, hold the test tube parallel to the chart and adjust the distance (about a half-inch away) from the chart until the color is uniform within the tube. Be sure to hold the chart at an angle that shows the colors on the chart best, while comparing the colors.

Many reviews complain that this kit doesn't test very low phosphate levels, and they are right. However, there are reasons to want to test for high phosphate levels ranging up to 10 ppm. For those that want to differentiate between fractional phosphate readings below 3 ppm, get the Salifert test kit. I use both, but in a planted tank using the highly regarded Estimative Index approach to fertilizers, you will often find phosphates going much higher than the 3 ppm upper limits. In a planted tank, you should not be concerned about trying to achieve low phosphate levels. You should be concerned about achieving balanced phosphate levels and that means phosphate readings in the 3-10 ppm area can be ok. Algae does not expand simply because of high phosphate levels in a planted tank.

I love all of the API products. Their test kits are easy to use and are all calibrated to use the exact same amount of water in their sample tubes. This is super convenient since you do not have to keep track of which tube goes with what test reagent.

Some pet stores don't normally stock test kits for Carbonate Hardness, but it is a very important parameter of water quality. Even for fish species that are not particular about water hardness, having enough Carbonate in a tank's water is a major help in preventing the water from becoming to acidic. As debris collects in the sand or gravel of a tank, its decay can cause the water to become more acidic over time. Carbonate not only lowers acidity of the water, but more importantly it acts as a buffer that helps to stabilize the PH of the water. Even fish and plants that can tolerate different acidity levels, are very sensitive to rapid shifts in the PH of the water. Rapid shifts in water parameters are almost always bad for fish and plants. The only exception might be that if your fish are gasping at the top for oxygen, getting more oxygen into the water quickly with aeration and surface turbulence is never too fast.

If the ammonia levels in a tank rise, this can also make the water more acidic. The more acidic the water becomes, the more toxic to the fish the ammonia becomes as well. Many things can cause shifts in the PH of the water, and Carbonate helps prevent slow and prevent these shifts that can kill fish and plants.

The Carbonate Hardness doesn't normally need to be checked as often as other water parameters. I normally check mine about once per month, so this test kit will last me for a long time even with several fish tanks.

I bought this kit because I had a Betta with what appeared to be fin rot. I suspected it was actually fin biting, but decided to monitor the tank's ammonia levels anyway. This kit is by far the most economical - for the amount of tests included for the price.

After 2 weeks of 0-.25 readings without fluctuation, I wondered if the tests were even accurate. I decided to test 5ml of pure ammonia instead. Imagine my disappointment when the pure ammonia sample turned the same yellow (0%). Before you go sending hate mail to API, there's a good reason for this. It turns out, the ammonia level was too high and essentially "blew out" the testing liquid. API is assuming your fish isn't living in pure ammonia and, therefore, didn't make this kit to test levels that high.

Next, I tested 5ml of water from a 1 gallon jug filled with tap water and 1 drop of pure ammonia. Yes, I apparently have too much time on my hands and a latent mad scientist gene. This test proved accurate. The tube turned dark green almost instantly (picture attached). I feel much more secure using and believing this test now.