Water-quality triage
Enter the readings you have. The checker prioritizes oxygen, ammonia, nitrite, chlorine, and sudden tank-wide changes without assuming one universal range fits every fish.
Free to use. Runs locally in your browser. No account required.
Leave untested values blank. ppm and mg/L are treated as approximately equivalent for these hobby water-test readings.
How it works
Use the result to decide what to verify first. Species requirements, test chemistry, recent changes, and the direction of a trend can matter more than one generic target.
Both are expected to be undetectable in a stable, cycled aquarium. A detected result matters more when several fish are affected, breathing is abnormal, or the biofilter may have been disrupted.
The calculator only flags very broad outliers. Do not rapidly chase a generic pH or temperature number without checking the fish's normal range, source water, and how quickly the value changed.
Gasping, several affected fish, sudden deaths, or a recent filter, water-change, power, heater, or chemical event can justify immediate aeration and verification even when some values are missing.
FAQ
Zero is the usual target for both. Any detected amount deserves review, especially in a new aquarium, after filter disruption, or when fish are breathing hard or several fish are affected.
Total ammonia includes forms with different toxicity. A larger fraction can be present as more toxic un-ionized ammonia at higher pH and temperature, so one TAN number is not the whole picture.
No. A snapshot can miss a recent spike, and disease, toxins, aggression, diet, and species-specific problems can occur even when the entered readings look broadly acceptable.
Low oxygen, suspected chlorine, extreme pH, significant ammonia or nitrite, and tank-wide gasping after a filter or water event can require immediate water-first action and experienced help.
