I have an 80 gallon tank (48 in long) and want to add a second sponge filter to put more oxygen in my tank. My first sponge filter is at one end and I was planning on placing the second filter at the other end, but I have noticed my fish seem to like to hang out on that side. Could the fish be stressed out by/scared of the bubbles and as a result are choosing to stay in the calmer area of the tank? If so, should I reconsider where I put the second sponge filter? The fish I have are: 2 albino cories (I plan to complete the school as soon as I find more albinos) 3 serpae tetras (also planning on getting 3 more) 12 guppies (species unknown) I also have a Cascade 1000 canister filter, so I am not relying on the sponge filters alone.