jdhiu99

Just setup a new 75 gal freshwater tank with two Marineland Emperor 400 hanging filters with bio-wheels. My concern is whether these two filters will provide enough aeration or not. Any comments or suggestions would be appreciated! Thanks.

Jay

Hi

Great, 75s are my favorite.

Gas exchange (oxygen dissolving in the water) takes place at the surface. Those two filters will increase the surface turbulence slightly and thereby speed up the O2 dissolving into the water. The biowheels and spray bar assemblies will also contribute. IMO you will be fine.

There is some confusion out there about this. O2 is extremely slow dissolving in water. Running, say, an air stone does not increase the O2 in the tank, it is the surface agitation caused by the bubbles that speed up the process. the bubbles shooting to the surface just look nice.

Jay

jdhiu99

Thanks for the help!

ahill3780

Well that is not entirely true. True enough that the bubbles do not always contact the water long enough to really dissolve the oxygen constantly, but they do contribute some oxygen dissolution into the water column. The major contribution is the effect it has in moving the water from the bottom of the tank up towards the top of the tank where the bulk the exchange occurs. However, oxygen dissolution occurs anywhere that air contacts water, and the longer that contact the more chance of the O2 making it into the water.

FYI, gas exchange is two part in an aquarium, and indeed it does happen at the surface of the water (still or turbulant - although turbulance is more desired by far). First off is the intake of oxygen particles into the water, and the second is the release of pent up nitrogen from in the water out into the air.