Thank you Scott!! I was beginning to think that I wasn't going to get any responses. I don't know the price of the B5 yet, just found out today that a local station has it. But, I'll be sure to check it out and get some more filters on order. Mine are basically brand new, so I'm hoping they'll filter pretty good for a while. If I start to use the B5, I guess I'll just have to hold on to the additive for when I'm traveling and Bio may not be available.