Primo, a simple fix to lower the filter output is to attach a sponge to the outflow of the pump. This slows down the current very effectively. Another option is to cut slits in the tubing that carries the water back to the display side. Have fun and keep up on the water changes, I've got a betta in my spec and he loves it. Water changes are the main focus on small tanks. Keep those up and your fish will do well.