Diagnosing and Fixing Aquarium Water Issues

Your aquarium's water quality is in a constant state of flux, since fish eat and produce waste in the water they live in. Ensuring the water in your aquarium is optimally balanced helps keep your fish happy and healthy.

Fish can get stressed and sick from problems with their tank water — even fixing those problems can hurt them if you make changes too rapidly. Optimal aquarium water quality is your goal, but heed this advice: if it ain't broke, don't fix it, and if it is broken, fix it gradually. 

Read on for some common aquarium water quality issues and how to dive into diagnosing and resolving them. 

Identifying Aquarium Water Problems

Some aquarium concerns, such as algae and cloudy water, are an obvious indicator of an issue to investigate. Other water quality problems are invisible and cause your fish to suffer before their signs of distress are apparent. 

Regularly testing your aquarium water helps identify both visible and invisible water quality issues before it's too late and helps diagnose problems so you can treat them correctly. With Aqueon 7-in-1 Aquarium Test Strips, a dip of the strip and 30 seconds assesses water quality factors like pH, alkalinity, water hardness, and levels of nitrates, nitrites, free chlorine, and iron. A handy chart indicates acceptable levels for each. 

Causes of most aquarium water quality problems include overfeeding your fish, an overpopulated tank, poor filtration, and replenishing water incorrectly. Preventing the problems in the first place minimizes the need for interventions, and as a bonus, reduces the stress on you and on your fish. 

Cloudy Water: Sometimes There's No Need to Intervene 

Aquarium water that's not crystal clear isn't necessarily a problem. In a new aquarium, cloudy water can occur because beneficial bacteria aren't yet properly established. After checking that the ammonia and nitrite levels aren't climbing (you want both at zero), it's best to wait to see if the problem resolves itself. 

In an established tank, the murky water's color and further testing can help diagnose the problem. Here's more detail on how to fix cloudy water plus how to prevent it in the first place. 

Keep Algae Growth in Check

A little algae in an aquarium isn't necessarily bad, because algae helps remove pollutants from the water. However, excessive algae is unsightly and can indicate fish-threatening water problems, like too much nitrate and phosphate

Regular water testing helps you diagnose any issues. Typical tank troubles — overfeeding, overpopulating, and insufficient additions of conditioned water — can cause algae, as does too much light. Learn more about how to prevent and control algae, the causes and cures of green water, and how to choose the right aquarium light.   

Use test strips to ensure nitrate levels are below 50 parts per million (ppm) and phosphate levels are close to zero. And remember that aquariums can have both nitrates and nitrites, with nitrites the more significant problem. An easy way to distinguish: nitrites with an "I" make your fish ill much faster than nitrates with an "A."

Treat and Remove Nitrate and Phosphate

Not only do nitrate and phosphate contribute to algae problems, nitrate stunts fish growth and, if exposure is too high for too long, compromises your fish's immune system. 

Keep nitrate and phosphate levels low by replenishing your aquarium with conditioned water; with algae removal tools like algae scrapers and algae cleaning magnets; and by using a mechanical filtration system, perhaps with specialty filter pads, and cleaning it regularly. This handy aquarium cleaning checklist will make your cleanings easier.

Aquatic plants can help too, simultaneously giving your fish a place of refuge and creating natural beauty in your aquarium. Caring for your aquatic plants is easy with a few simple steps.

Raise and Lower pH Safely 

Aquariums for most tropical fish should have a neutral and stable pH between 6.8 and 7.8. The pH scale measures acidity and basicity: it ranges from 1.0 (acidic) to 14.0 (basic), and 7.0 is a perfect neutral. The usual aquarium issues — overfeeding, overpopulating, and unconditioned tap water — all affect pH. You likely won't need it, but just in case, here's more on how to safely adjust your aquarium's pH, including with driftwood, coral, and gravel.

Fix Ammonia Levels Above Zero

Ammonia in an aquarium is a serious problem. It damages fish gills and internal organs and can be deadly. Ammonia test strips verify that your ammonia level is zero. Ensure you don't introduce ammonia into your aquarium via unconditioned tap water and that ammonia doesn't build up via uneaten food or from the waste your fish produce. Aquarium plants and filters help deal with ammonia, as do products like ammonia neutralizers.

Remove Other Toxic Compounds

When bacteria break down ammonia in your aquarium, it causes a rise in nitrite levels. Like ammonia, nitrite can kill your fish. They can suffocate because nitrite makes it harder for their blood to carry oxygen. An ammonia or nitrite level above zero isn't safe for aquarium fish. Changing a portion of your aquarium's water helps resolve a nitrite spike, but it's best to prevent the problem in the first place.  

Conditioning water before adding it to your aquarium alleviates many water quality problems. Municipal water often has added chemicals like chlorine and chloramines. They kill microorganisms that make humans sick but burn fish gills and make it hard for them to breathe. Chlorine evaporates from water if you let it sit for a few days, but chloramine needs a de-chlorinator or water conditioner. When you add water to your aquarium, always use a water conditioner to neutralize chlorine, chloramine, ammonia, and other toxic water compounds.

Assess Your Water Quality Regularly 

To help prevent and resolve water quality problems and ensure your fish thrive, use tools in your aquarium such as filter systems, pumps, aquarium lights, water care products, and test strips. Want more tips? Check out these five ways to know your fish are happy and healthy.