I have a 55 gallon freshwater tank set up with a couple miscellaneous fish in it. It came with a top fin 75 filter and I decided to add another filter to the other side of the tank. I also added a couple new plants to the tank at the same time. A couple hours after setup I noticed small bubbles accumulating on the surface of the water. The bubbles were small and difficult to pop so I scooped them up with a net. Any ideas why these bubbles would start now that there's better filtration than before?