Photosynthetic bacteria (PSB) are consumed as they break down toxins like ammonia and hydrogen sulfide, with their activity typically dropping below 50% within 5–7 days. During periods of low light (e.g., cloudy weather) or when water temperatures fall below 15°C (59°F), their reproduction halts, requiring manual supplementation to maintain an effective population. Harmful bacteria (such as certain anaerobic strains) can rebound in just 3–4 days; regular addition of PSB helps establish a dominant, beneficial microbial community that suppresses them. Given that koi continuously produce new waste, it is recommended to supplement at a rate of approximately 200 grams per ton of water weekly to meet ongoing detoxification and metabolic demands, ensuring consistent water quality and a healthier environment.
