I personally consider biowheels a gimmick. Sure, they hold bacteria. But the walls of the tank, the intake pipe, the substrate and any decor in the tank holds bacteria, too. I don't see the amount of bacteria contained in a biowheel is massive enough to make or break a cycled tank. After all, when's the last time someone suffered a mini-cycle when their biowheel stopped spinning (killing most of the bacteria) or when they remove the biowheel for a replacement or because they're tired of keeping the thing spinning?
Honestly, I am very much in favor of canisters. A lot of people shy away from them, but they are not technically difficult to use. And if you want to talk about biomedia, just look at how much biomedia you put inside of even a small canister (Rena XP2) as compared to the thin sliver of media you can put into any HOB cartridge slot.
Further, when you add up the amount of money it takes to keep replacing those HOB cartridges, it doesn't take long for the price tag to go very high. Have you ever wondered why the filter manufacturers don't make a standardized filter cartridge for their HOB filters? It's because the money isn't in the filter itself, it's in the constant purchasing of those cartridges. They want to make sure you buy their media cartridges so they get your money, not someone else.
Canisters are much easier to maintain, much more stable running, much quieter, and much, much better at doing an actual filtering job. Not to mention that they can be setup so that they don't break the surface water which degasses the CO2 from the water.
And, no, I don't work for any canister company or profit from whatever is purchased in any way. I just like canisters better. I started out with two Emperor filters and simply could not polish the water like I wanted. So I finally tried a canister, and wow, was I impressed. Made me wish I hadn't wasted so much time and money on the HOBs and cartridges. I have not found one person who regrets buying a canister and wishes to go back to an HOB so I have a feeling I'm not alone in preferring a canister so much more.
Many people buy HOBs to avoid paying more for a canister. But when you consider the price of a canister against the constant expense of replacing cartridges for HOB filters, usually, a canister saves people money in the long run. Just something to consider. :smile: