No need to open the oxygen pump, always open the filter pump can be, the water flow into the water has enough oxygen, my tank and your tank is the same size, the fish are almost the same, only open the filter pump, and it is with a timer on 15 minutes off 15 minutes, there is no problem at all, if you are still worried about dissolved oxygen is not enough, and not afraid of noisy (in fact, it's not noisy), you will be the outlet out of the water surface of the surface of the water a few centimeters, so that the oxygen into the water There will be more, mine just put the outlet pipe mouth into the water.