You would start to employ other forms of export when your system cannot keep up with normal operations and maintenance routines.
So, as an example.
I started with just carbi-sea dry rock and sand, and a skimmer.
I starting adding a fish or too each month to watch the effect the additional loads on my maturing system. In 8 months we had all the fish going, 10 including 4 tangs. During the later stages, nutrients were increasing on a regular basis, so, I started to carbon dose for a few months.
Over the next two years, the tangs got big, so bigger wastes, nutrients starting rising again, so, I added fuge for additional processing and now after 3 years, no further filtration is needed.
At the same time, I added corals almost weekly, they have a small impact on processing, but mop up some.
Now that the corals are big now, I’m starting to see lower nitrate values (yesterday 1ppm) when for a year, she stayed 5ppm.
So, for a month now, I’ve had to dose some Neo-nitro to put it back at normal operating levels.
So, full circle in 3 ish years, from pulling too much, too adding directly.
Maybe something in this rant my help you.