I've been browsing this forum for a while now, so I thought it was about time I actually posted. I've owned a few aquariums up until now - all tropical freshwater. Recently, I bought a 125l tank which I really want to deck out and spend a lot of time/money working on. Though I've loved my past tanks, they didn't get much TLC due to study and work commitments, but now I have a bit more time on my hands to really go to town on a nice setup. I'm putting together a wish list of all the things I want to eventually have in this new tank. Currently, I have the filter and heater that came with it, but I'm hoping to replace the filter with an external one with a bit more kick. I'm also planning to invest in a CO2 system to give my plants some love. Anyway, I've recently been reading about bio-wheels and the huge amount of good they can do when it comes to biological filteration. My question is, is it worth having a bio-wheel in addition to a cannister filter? Or would the bio-wheel just be redundant? The filter I currently have is a Fluval U3. My tank is planted, soon to be heavily so. It currently only houses a few cherry barbs, but I'm hoping to add some shrimp and other small shoaling fish over the next month or so. Thanks in advance for any help.