Aquarium Water Test Kits

Mother and baby looking at aquarium.
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Testing aquarium water is a key component of maintaining a healthy environment for fish. The question is, what should be tested? Is there a difference between test kits? This list of aquarium water test kits helps sort what to test for ​and provides information about what products are available.

  • 01 of 10

    Master Test Kits

    Combination, or Master, test kits are touted as the perfect way to have all the tests you need on hand. But are they worth the money? The pros of buying a combo kit are lower cost per test, everything has the same expiration dates, and it’s a quick and easy way to purchase and keep the basic tests all at once.

    The downside is that one can’t customize tests; the kits are fixed to what’s in the kit. Another complaint many have is that like much the printer ink cartridges that came in a bundle rather than separately, the kits tend to run out of one item long before the others. What should be done? It is recommended that keeping a master kit on hand with pH, ammonia, nitrite, and nitrate, preferably a liquid variety instead of strips is best.

  • 02 of 10

    Ammonia Test Kits

    An ammonia test kit is one of the must-haves for every aquarium owner. However, not all ammonia tests are created equal. The primary issue at hand is the fact that ammonia can be present in a non-ionized form (NH3), or the ionized form (NH4) known as ammonium.

    NH3 is what hobbyists are concerned about, but most tests give results for the total of NH3 and NH4. Most ammonia test kits on the market give you only the total ammonia value. Seachem kits reliably test for both total and NH3, however, the kits cost more than the types that test only for total ammonia. Seachem also produces in tank ammonia alert products which are generally good but are not as reliable as actual liquid test kits.

  • 03 of 10

    Nitrite Test Kit

    Nitrite is another test that is important during the start-up of a new aquarium, as well as on an ongoing basis to catch problems before they become serious. Once you have your tank well established, It can be that recommend testing for nitrite monthly and any time a fish is sick or dies is advisable.

    It is preferable to use liquid test kits, but if the budget is tight, using test strips are better than not testing at all. It is common to see combo test strips of nitrite and nitrate, however, nitrate testing is not as critical so save your pennies and opt for nitrite only strips if you are on a tight budget.

  • 04 of 10

    Nitrate Test Kits

    Nitrate is not as dangerous for fish, but at high levels it stresses them, leaving them more susceptible to disease and ultimately shortening their lifespan. If it is desired to breed fish, keeping nitrates low is a must. Elevated nitrates are also a major contributor to algae growth. For all those reasons, it’s wise to track nitrate levels regularly in any aquarium.

    Nitrate tests are often included in a master test kit or paired with a Nitrite test kit, but they can also be purchased separately. As with other tests, liquid test kits are preferred. However, if cost is an issue, the strips will do.

    Continue to 5 of 10 below.
  • 05 of 10

    pH Test Kits

    The pH is a key parameter for all aquariums and should be tested and recorded in a log on an ongoing basis. Sudden changes in pH are often the invisible cause of fish disease and death. Gradual pH changes are less serious in the short term, but ultimately can be just as dangerous to the health of fish. If using strips instead of liquid test kits take care to seal the strips well and don’t touch the pads on the strips with dirty fingers.

  • 06 of 10

    Hardness Test Kits

    Hardness, which actually refers to the levels of dissolved minerals, is not as commonly tested. However, it has a direct impact on the stability of pH and the species of fish that will thrive in the tank, making it an important parameter to at least get a baseline reading of. Two types of hardness tests are available, KH or carbonate hardness, and GH or general hardness.

    KH, often referred to as alkalinity or carbonate hardness, is the measure of carbonate and bicarbonate in the water. The higher the KH, the more stable pH will be. GH measures the levels of dissolved magnesium and calcium, which is what we refer to when using the terms hard or soft water. GH should be matched to the species of fish being kept. For instance, Tetras do best in softer water, while most Cichlids thrive in hard water. GH is particularly important when breeding fish.

  • 07 of 10

    Phosphate Test Kits

    Generally, this test is most often used in saltwater aquariums. Phosphate is not a commonly used test in freshwater aquariums, as elevated levels will not harm fish. However, phosphate is a key factor in algae growth. If battling algae problems, knowing the phosphate level can help determine if the steps being taken to lower the phosphate levels are having the desired effect.

  • 08 of 10

    Oxygen Test Kit

    Oxygen is rarely tested in aquariums, but there are special situations where it is useful. Densely populated tanks, such as those that breeders might have, or densely planted tanks are two situations in which oxygen levels may require closer examination. Both salinity and temperature impact the amount of oxygen that can be dissolved in the water. Warm water holds less oxygen than ​cold water, and freshwater holds more oxygen than saltwater.

    Continue to 9 of 10 below.
  • 09 of 10

    Iron Test Kits

    Iron is present in trace amounts in aquarium water and generally does not require testing. However, plants require iron to thrive, and those who keep heavily planted tanks, or breed plants, may test for iron levels.

  • 10 of 10

    Copper Test Kits

    Copper tests are only used in situations where copper is used to treat sick fish. Because it is used only during treatment, this is not a test kit that is normally kept on hand. Instead, copper test kits are usually purchased when giving copper treatments.