Measure and add context
Record the baseline and check ammonia, nitrite and temperature during startup or trouble. Do not infer the aquarium's condition from a single sign. Record method, time, temperature and recent changes so the reading can be compared.
Then compare nitrate, pH and hardness for the source and livestock with livestock needs and recent changes. Assess the trend alongside breathing, behaviour and species requirements.
Correct without destabilising
Adjust one variable and assess a dated log including method and context before continuing. Keep a reference so the result can be compared. Address exposure or cause first, then retest before stacking products or interventions.
More kits add little value when no action is attached to each result.