if it's for the 5.5 dp tank, I think it's too small. the Azoo Palm Filter is really designed for bowls or small tanks (probably 1.5 gal or less). my rule of thumb for filtration is, try to circulate 10X tank volume per hour. So for the 5.5 gal, strive for at least 50 gallons per hour of filtration.
With hang-on-tank filters, an easy way to increase aeration is to lower water level. that way, the splashing action of the water returning to the tank is enough to oxygenate the tank.