I purchased the Azoo Oxygen Plus Bio-Filters #7 which does not come with the extended tube like filter #4 does. I was told by someone on another thread here that the extended tube that comes with #4 allows you to change how the air is distributed. (it can be made into steam at the top of the tank). Is this a big deal? PRo's and cons? I have filter #7 and to return it I'd lose the $5.99 in shipping plus have to pay to ship it back. All for a $6.99 filter. That said I want to make sure I get a good filter. I"m not currently using any other filters in my tank (sponge filter is not set up just the bubbler) so I want to make sure I have the right one.
also I've heard of people using CO2 filters. Are these different? How do I know if I need one?