freshwater tank airation

Question
I started out with a 5 gallon, then a 10 gallon, and now I'm moving up to a 75 gallon fw tank. One thing I've noticed is the difference in filters, the old filters poured the water back into the tank from above water level and I assumed this was to keep adding oxygen to the water, but my new tank filter reinserts water below the water level, it is a fluval 404. Is this incorrect and do I have to somehow add oxygen to the water. I don't have fish yet while the tank is acclimating, but I plan on having some fw flounder and some green tiger barbs, and possibly some live plants, Any tips would be appreciated! Thank You.     Larry

Answer
Hi Larry;

How exciting! That's an excellent size tank. Your filter should work just fine. They don't have to make water come in above the surface in order to oxygenate the water. The surface of the water still moves quite well to allow exchange of gasses such as CO2 and Oxygen. Look at the top and you will see it. Just a bit of turbulence. That is really all that's necessary. I have a Fluval 304 canister on my 55 gallon. I added a 12 inch airstone that runs with a good sized air pump, partly for extra circulation, partly because I like the effect. You could easily do that in yours too. However, without the air pump and bubbles your tank would be much quieter. It's up to you and depends on what you want.

Have Fun!

At Your Service;
Chris Robbins