Airation question

[xDestro]

I just installed a corner matten filter in my 20 long and I plan to have a air stone behind the sponge, would that provide the water outside the sponge with air? Or would I need an air stone outside the filter?

 

[FreshyFresh]

A 20L has a lot of surface area per volume of water. Even the gentile surface agitation that corner matten provides will aerate the water well.

 

[xDestro]

Awesome! Thanks

 

[duanes]

Air does not actually come into the water from the air stone.
The aeration comes from the bubbles breaking the surface, and allowing air exchange by breaking surface tension, and providing water movement.
If the filter blocks water movement on the tanks surface, another air stone to add more water movement would not be a bad idea.