N is high in fish food relative to P. So P will always be in a lower ratio to N as far as plant needs.
Carbon is quite another issue entirely. Far more carbon as CO2 will enter through the air above than the food source. That carbon source is stored and eventually will be used by algae, plants, or gassed off, just like C02 enrichment. We have done Carbon tracer studies at UC Davis here. The Carbon atoms can be traced through a systemand relative % of each source of carbon, such as the % ratio from fish food and the % from the air and other sources can be determined.
Also, the tap water and the source water for water changes plays a huge role. Simply feeding more vs changing the food type may give you the same results, I suspect prior, you were N limited, rather than some C/N ratio issues.
Regards,
Tom Barr |