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In the article, The Nitrogen Cycle, I talked about the how nature provides for a way to naturally clean the waste from your fish tank. Unfortunately, the bi-products of this process creates chemicals that can adversely affect your fish and other tank inhabitants. These bi-products, Ammonia, Nitrites and Nitrates are very important in maintaining a healthy aquarium eco system. However, there are other chemicals that are just as important and that also require monitoring to ensure a healthy aquarium. Anyone wanting to be successful at keeping a tropical aquarium must put forth the time necessary to understand some basic fish tank water chemistry. This will help your fish to not only survive but thrive!
If you want your aquarium (freshwater or saltwater) to thrive, then you’ll need to know how to test your tank water with an aquarium water test kit. There are many chemical tests kits on the market that will test for each of the following:
- Ammonia
- Nitrite
- Nitrate
- Salinity/Specific Gravity
- pH
- Carbonate Water Hardness
- Alkalinity
- Chlorine and Chloramine
- Copper
- Phosphate
- Dissolved Oxygen
- And others
Some of these kits group a few of the more common tests into a “Master Test Kit.” Buying these Master Kits can same you a little money as buy each individually can be expensive. For most casual hobbyists, these master test kits will be sufficient. However, lf you plan to have live flora or a marine aquarium, you may need to invest in additional specialized mini test kits such as copper, phosphate, dissolved oxygen, etc.
Most kits come with a color coded results strip that you either dip into a sample of the tank water then compare to a color chart or you mix the test with a sample of the water in a test tube and then compare to a color chart. Both methods work well. However, it can sometimes be difficult to match the test color to the color chart. It can sometimes be helpful to get a second opinion to help match the colors.
The Master Test Kits usually contain tests for ammonia, nitrite, nitrate and pH. However, each tech can be purchased separately as replacements. The following list will contain the chemical you need to test for and a corresponding kit. I will try to present kits from both a high and low price range and will include which type of media it will test (Fresh or Salt Water).
Alkalinity / pH
pH test kits may test only the range that is relevant to certain freshwater or saltwater environments, so make sure you get the right one. Significant pH changes are fatal, and can be prevented with stable alkalinity. Regular use of pH and alkalinity test kits is the only way to spot trends and problems that need to be immediately addressed.
pH varies slightly over time; we recommend testing at the same time of day, every 2 weeks or more frequently if establishing a new tank. When bringing home new fish, compare the pH of its old water to yours, and slowly acclimate it to its new habitat
It is possible to raise or lower your pH levels with water changes or chemicals (use extreme caution!) from your local pet store. However, I do not recommend this. Below are a few suggestions for naturally changing your tank pH.
- If you need to raise the pH in your tank, try doing a partial water change with water that has been aerating for several hours. Doing this can raise the pH of the tap water significantly.
- Gravel, depending on the type, can raise or lower your tank’s pH. Any decor like corals or fossils hikes your tank’s hardness and hence your tank’s pH.
- Decorations like driftwood or bogwood can lower pH.
- High nitrate levels lowers pH. However, don’t use high nitrate levels as a means of reducing pH. High nitrate levels are highly stressful to fish.
- Water maintained under higher temperature also tends to be acidic.
- If you have a live flora, you can observe considerable pH fluctuations during day and night hours. When there is light, plants carry out photosynthesis, taking in carbon-dioxide and giving out oxygen. This raises your tank’s pH. At night, plants respire, taking in oxygen and giving out carbon-dioxide. This reduces pH. This is why it is important to take pH measurements at the same relative time of day. Otherwise, you may detect these naturally occurring changes in pH.
- Pumping in carbon-dioxide for the well-being of plants also lowers water pH.
Ammonia/Nitrites/Nitrates
These chemical are the result of fish waste and decomposing food in the aquarium and are bi-products of the Nitrogen Cycle. Do not minimize these tests. Ammonia/Nitrites are the leading killer of tropical fish. Nitrates can significantly change the pH of your tank and can cause overwhelming algae blooms. In a new aquarium you will see a spike in first ammonia and then nitrites. This is normal and both will eventually come down. You want to keep Ammonia and Nitrites at or very near zero. If you notice constantly high levels for theses chemicals, first do partial water change and then examine your biological filter as something is not working correctly. Nitrates are not a toxic as ammonia or nitrites, but they are harmful and will stress your fish at high enough levels. The only way to reduce nitrates is through partial water changes.
Chlorine /Chloramine
Tap water contains chlorine or chloramine (chloramine is more aggressive but essentially the same thing) for sterilization purposes. Chlorine and chloramine are toxic to aquatic life and cause immense stress and damage. Use chlorine and chloramine test kits to test your tap water before setting up a tank or doing a water change – if you have either, use chlorine removers.
Copper
High levels of copper are toxic to aquatic life, but is necessary in the treatment of certain parasites. You will need to use copper test kits whenever you use copper-based medications to make sure levels don’t get too high. (Use a quarantine tank to prevent problems in your main tank.) Once treatment is complete, you can use activated carbon to filter any copper out. Copper should not be used or evident in aquariums with invertebrates or planted aquariums.
This cooper can also be found in tap water if you have older copper pipes. So be sure to test any new water used in water changes before adding to the tank.
Dissolved Oxygen
Oxygen test kits tell you how much dissolved oxygen there is in your aquarium water. Fishes need oxygen to live, and any aquarium needs proper aeration. Large tanks can suffer “dead zones” – areas that aren’t getting oxygen – without adequate water circulation. Water pumps provide the most circulation; in a large tank you may need an air pump too, or an aerating water pump. Smaller tanks can often get by on an air pump alone.
Use oxygen test kits weekly if you have a large bio-load or a large tank, or to make sure your aeration setup is adequate.
Phosphate
Phosphate can be introduced to your aquarium mainly from tap water, dead plants and fish food. High phosphate levels can cause algae outbreaks. There are products on the market to remove phosphates and you can do your part by keeping up with your aquarium maintenance and performing regular water changes.
Salinity
Aquarium hydrometers and refractometers measure the specific gravity (density) of water, which is determined by the amount of salt saturation. Refractometers are more expensive, but also more accurate, so they are a good investment for the committed saltwater aquarist. Keep your salinity constant by replacing evaporated water regularly. (Don’t use saltwater for top-offs, only water changes – salt doesn’t evaporate.)
Water Hardness
The hardness level of water has to do with the amount of minerals that are dissolved in the water. Calcium and magnesium are the primary minerals that are dissolved in tap water. “Soft” water has relatively few dissolved minerals whereas “hard” water has many dissolved minerals. Water hardness is not really an issue unless your water is excessively soft. Then you may have problems with runaway pH levels. For saltwater aquariums this is especially true. The carbonate hardness of saltwater can give you a good indication of how stable your pH is.
Proper hardness creates the right environment for your organisms, and affects pH stability. In reef aquariums, calcium processing requires a higher GH. To increase hardness, use buffers or add crushed coral or limestone to your tank or filter.