I just did some reading up on Purigen and it seems to be an impressive product. It says that it controls ammonia, nitrites and nitrates. If that is true then it sounds like it will probably replace my bio-filter. If that is case then it seems that I will be dependent on Purigen as all the current BB in my filter will be dead. If I was to eventually remove the Purigen, I'm guessing I would have an ammonia spike. Has anyone had this happen before?