zeovit Stones [Zeoliths] are just a place for bacteria to grow. just like rocks, glass, and all other surfaces in our systems do. Due to high capacity of the Zeoliths .... they can colonize more bacteria than say ... Glass.
the reactor, is just an upflow ... it makes sure you get uniform flow through all the stones, so you use all the stones ... and that is it.
there is no connection between Zeoliths and Zeobac. Zeobac can grow on any surface. even live rock.
Use of the Zeoliths, however, seems to process po4 much better.
about the question of how we can tell Zeobak is working .... we cant to be honest ! problem here is no3 not reducing even though carbon is dosed. This can be due to many reasons, one of which is no bacteria in system .... so IFF thats the reason, then Zeobak can help. but again ... that might not be the reason so ...
Zeovit system with no stones can work, with LESS efficiency.
stones make it more efficient.
reactor makes it even more efficient. [100% of stones used where as passive stones might develop channeling and not 100% of stones get same flow. ]
HTH,