What is the bio cycle within your pond?

This is the graph of biological cycle creation path way with some durations this was arranged for tropical environment but for the colder environments this becomes slower & it takes double time period than tropical environment

As per this chart very first Nitromonas start their work and their activation come to peak on after start 12 days & Nitrobacter start their work parallaly with receiving Nitrite and they come to peak within 24 days. In this process ph becomes get lower until 5.5 ph.

Please concern on this after 6.5ph koi fish become stress & after 6.0ph koi fish come to danger zone. So you have to aware on your fish within this time period. The water ph should be gradually need to increase by developing water carbonate hardness(KH). For this refer my blog page how to adjust KH?