you must have a really big tank, isnt the dose like one capfull per 200 litres at water change?
I'm using it to setup my new tank, but once the bottles gone I wont be getting anymore, once you have a healthy bacteria culture you shouldnt need anymore, unless you are repeatedly killing your bacteria culture in the filter, like washing the bio media in chlorinated water or something like that.
continued use of "cycle" is for the paranoid and the clean freaks.\
miss a couple doses and do a nitrite and ammonia test, every day, if the ammonia and nitrite dont go up, then your tank is safe wihtout "cycle",
Doug