not that it has any relevance but why don't you use tilapia in your system? i know that koi are extremely hardy fish but why not capitalize on something a bit more edible? and do you use any specific proportions of # of fish per gallon in your reservoir? how many plants should be grown per sq ft within a system with x amount of gallon system pumping and x amount of dissolved fishwaste so that the nutrients are equally distributed? or does it even matter being that all the fertilizer is organic and is dispersed by adding other species of plants to the system (ie tomates, other herbs, etc)?

I think I like to develop a basic system at first to sustain 7 to 10 large plants