Which of these 4 power filters for a 50 gallon tank?

[bif24701]

So, the Fluval provides O2 to the fish? (Do I need one of those bubble blowing things?)

No, the filters provide 02 to the nitrifying bacteria in the filter, by bringing in water from the tank and the water flows around the Bio Max then back to the tank.

 

[mfdrookie516]

So, the Fluval provides O2 to the fish? (Do I need one of those bubble blowing things?)

All filters do to some extent (Unless steps are taken to prevent... like in a high tech planted tank). Not by filtering the water, but by disturbing the fsurface creating better gas exchange...

But...

No, the filters provide 02 to the nitrifying bacteria in the filter, by bringing in water from the tank and the water flows around the Bio Max then back to the tank.

this is also true. It's kind of a combination of both

 

[Gnarls Gnarlington]

Okay, thanks guys. My last tank was "old fashioned" I guess. All it had was an air pump to carbonate the water. LOL!