You have the assumption that ...

You have the assumption that you have sufficient Phosphate and Carbon for the bacteria to live.   I set up a system where the main food source was Carbon with no nitrogen and no phosphate.  All living organisms must have all three.  We used urea and phosphoric acid mixture along with air injection and  a small injection pump to feed the bugs; it was very successful. Without the nitrogen and phosphate, the bugs just will not grow.