two filters - placement

[James_in_MN]

I have a 20g high with an Aqueon Quietflow 30 in it currently. I'll be adding a powerhead-sponge combo to it shortly for both added filtration and as a backup filter.

Does it matter where I place the new filter? It's only a 20g tank, so I'm guessing it doesn't matter all that much if they are at opposite sides of the tank, right?

 

[James_in_MN]

After thinking about this for a while, I've decided that two filters too close would probably work against each other, so I'll put the powerhead-sponge on the other side of the tank. My only concern would be an overabundance of water flow in the tank. The black neon tetras and five banded barbs play in the current now, but the bettas hate it. I may have to try the plastic bottle method to cut down the water flow from the HoB before placing the other.