when to flush w/ organics?

[Clackamas Coot]

I've never 'flushed' my organic grow soil. As a matter of fact, I re-cycle the 'used soil' as quickly as possible. I use rice hulls as a 'marker' for how old the soil actually is, i.e it takes about 3 cycles to break down rice hulls from my experience.

Flush what exactly? <shaking head>