How often do I need to use Natural Pond Cleaner?

When first using Natural Pond Cleaner, pour in bacteria weekly for 4 weeks or until desired water or bottom quality is achieved. Continue monthly at half the initial rate to maintain water quality. Usually bacteria will last up to 30 days in the pond; however, rainfall, outflow and evaporation can deplete levels.

How long is beneficial pond bacteria good for?

Sanco has several different forms of bacteria, liquid and dry. 
Our liquid Natural Pond Cleaner can last for more than 5 years if kept in a stable temperature unopened.  Once opened you should use Natural Pond Cleaner within 2 years.  Once opened and stored you may loose some spores over time. 
Sanco's dry packs and spikes can last at full strength up to 3-4 years.  Spores may fade over time, but some germination could be expected indefinitely.