Tracking fish tank water parameters means using an aquarium test kit, thermometers, and other tools to measure the chemistry. The water pH, temperature, nitrogenous waste content, and salinity are most important. Iron, phosphorus, copper, magnesium, and other tests are used by advanced aquarists for plant and coral enrichment.
Aquarium pH
Measuring your aquarium water pH is the parameter you will be checking most often. pH is a measure of the balance between hydrogen (H+) and hydroxide (OH-) ions in your water.
A higher concentration of H+ means you have acidic water conditions, where the pH is less than 7.0 (neutral). A pH greater than 7.0 is considered alkaline, or basic.
Aquarium water pH is measured on a logarithmic scale as well. Meaning a shift from 5.0 to 6.0 is a 10-fold difference in concentration. So what seems like a little change in pH is a big deal for your fish. We never want the tank water pH to change too fast.
What is the Best Water for Fish Tank?
Most of the fish you find in pet stores will do well in both mild acidity and mild alkalinity. But some have preferences that are important to match for spawning, longer lifespans, and disease treatment. As long as you avoid extreme water parameters aquarium fish will thrive in treated tap water.
Water Temperature
A basic thermometer will keep track of your water temperature. Some aquarium heaters come with one built in. Temperature should match what the dial displays. But a separate thermometer is important in case your heater has a shortage in its control mechanism.
Cold water aquarium fish like goldfish, paradise gouramis, and white cloud minnows will be fine at room temperature. Tropical fish need a heater that provides a stable zone of 72-82℉, depending on the species. The closer the native habitat of your fish is to the equator, the warmer the water conditions they will prefer.
Even tropical fish that will tolerate cold, like betta fish, prefer a heater. Without one, their metabolisms slow. They become more disease prone, lethargic, and live shorter lives.
What Rocks Raise pH in Aquarium?
Rocks are an excellent addition to the hardscape decoration but many will alter your water chemistry. They contain minerals that will cause the pH and water hardness (dissolved mineral content) to go up. Minerals to watch out for include the calcium carbonate that sedimentary rocks contain.
To test whether a rock will raise the pH of your tank, polish a section of the surface clean of dust. Add a few drops of vinegar and let it sit for a few minutes. Any bubbling or foam lets you know the rock will alter your water chemistry. The bubbles are caused by vinegar (acetic acid) reacting with the calcium carbonate.
If you have hard water fish like African cichlids or livebearers, it’s not an issue since these fish like high pH water parameters. Tetras, angelfish, loaches, and other soft water fish will be stressed, however.
Cloudy Aquarium Water
Cloudy aquarium water is caused by material floating in the tank. The source of the material affects how you treat the issue. Two of the most common are bacteria and algae cells, which are microorganisms that feed on excess nutrients in your water.
Microorganism blooms are stopped by removing excess fish food, dead fish, or other sources of nutrients. Too much light fuels green water algae, in particular. Putting your lights on a timer will soon clarify your water.
Suspended sediments from substrate dust and microbubbles from excess aeration will also cause white cloudiness. These two issues are easier to treat; by reducing water flow the dust or bubbles will settle out in a few hours.
You can then vacuum up the dust along the bottom using a siphon hose. And microbubbles won’t return unless there is a device in your tank that needs adjustment, such as a protein skimmer or canister filter.
Nitrogenous Waste Products
Nitrogenous waste levels are as important to track as your aquarium water pH. There are three compounds that form during the aquarium nitrogen cycle.
Ammonia and Nitrite Levels
Ammonia (NH3+) and nitrite (NO2-) are the two most dangerous forms of nitrogen. Ammonia is excreted by fish and is the first product formed by the decay of proteins and amino acids.
Ammonia is also a food source for several kinds of beneficial bacteria that live in your aquarium water. They eat it and excrete it as nitrite, which is less toxic but still poisonous to fish.
Ammonia and nitrite should always test at 0 parts per million. If you detect it in your tank water, there is an underlying issue. Excess food or dead fish may be decaying and releasing ammonia. Or your beneficial bacteria population may have decreased due to excess filter cleaning.
Aquarium Nitrate Level
After ammonia is transformed into nitrite, a second set of bacteria feed on it. Nitrite is released into your aquarium water as nitrate (NO3-).
Nitrate is much less toxic to fish health. Most species tolerate it anywhere from 10 to 40 parts per million. Invertebrates are more sensitive to it, however.
Nitrate accumulates in your aquarium water until you remove it through water changes. Plants will also use nitrate as fertilizer, though they prefer ammonia and nitrite.
Water Changes and Fish Health
Water changes are essential for a healthy tank. But too large or too frequent water changes will kill your fish. Aquariums thrive on stability, especially saltwater tanks. The same is true for freshwater tanks, too.
Even if your ammonia tests are high, it’s not a good idea to change more than 50% of your aquarium water at a time unless it’s life or death. Sudden additions of fresh water cause massive shifts in water chemistry.
Your pH, hardness, water temperature, and other parameters jump several degrees at a time. Even though you’re adding clean water, such a big shift may be fatal for your fish and invertebrates.
Small, frequent water changes are better than large, infrequent ones. When doing a water change you should also try to match the temperature of the incoming water to your tank. If the temperature is off by a few degrees, this isn’t an issue when doing a small change. But a large influx of cold or hot water can kill your fish.
I recommend 20% water change once per week or every two weeks if your filtration is excellent. Test your water parameters every week to ensure nitrogenous waste levels remain low. The pH should also remain stable over the long term.
Conclusion
Aquarium water parameter testing involves a little chemistry. But the more you perform them, the easier it becomes. A healthy tank is also a stable environment. Aquarium water needs little adjustment once you have it cycled and stocked with fish.
FAQs
You need to track several aquarium water parameters for a healthy reef tank. The pH should be 8.0-8.4, kept alkaline using a crushed coral (aragonite) substrate. The salt concentration (specific gravity) needs to be at 1.023-1.025. An alkalinity of 9-11dGH will keep the pH and hardness stable. Calcium levels of 400-500 ppm and magnesium levels of 1200-1350 ppm are also important for proper skeletal construction.
GH stands for General Hardness. It is a measure of the concentration of magnesium and calcium in your aquarium water. Soft water species like Discus need a dGH of 1 to 4 for spawning. 4 to 12 dGH is considered low to moderate water hardness and is suitable for most aquarium fish. dGH 12 or above is hard (mineral-rich) water conditions.
As animals, fish inhale oxygen and release carbon dioxide, like we humans do. Carbon dioxide is a weak acid and affects the pH. They also excrete ammonia as waste through their gills. Ammonia is a weak base and also affects pH. But the amount of CO2 and ammonia that fish produce are smaller influences compared to your rocks, tap water chemistry, decaying fish food, and other factors.
