We always want pictures, no matter what the question is.
The short answer is that you have the system optimally balanced when you are feeding as much as you can without losing water quality.
I have determined my system limits over the course of its first 6 months, tweaking and tuning along the way. To work actively to find my limits, I increased feed levels a little every few days and watched water quality. When water quality started to drop, I backed off on the food a bit to regain water quality. Then after a bit, I'd see if the bacteria had caught up by increasing feed a bit. Eventually I found an equilibrium on feed level, but then decided if I could turn over the water faster, I could increase the feed level. Bigger pump, bigger autosiphons, new plumbing...and then slowly raise feed levels.
Same methodology to find the right control for pH.
At this point, I know my system can handle 50g of feed a day, and needs 2-3 teaspoons of potassium bicarb to hold the pH at 7.0. I test about weekly unless something looks funny. Of course, once I get my hands on some oyster shell, I'll be tinkering with control of the pH.
It never ends.
