[audioaficionado]

Some O2 will dissolve from the bubbles, however the surface agitation and more importantly the continuous and rapid water turnover from the surface into the water column will be the vast majority of any oxygenation that occurs. The surface agitation is a good indicator of that turnover. CO2 is cheap and it won't cost much to double or even triple the bubble rate to compensate for any additional losses. Even if you have a low tech non CO2 tank, rapid surface water turnover will grab more airborne CO2 for your plants.

 

[audioaficionado]

Does anyone know how good a marineland magnum is ? I belive i mentioned it but everyones acting like there is only fluval and ehiem

I've only had Marineland Magnum 350 canister filter and it isn't dead silent, but it's not loud enough to be noticable over quiet conversation or TV/movies or at night. Works fine to keep my 45gal tank clean and water movement/turnover.