I was thinking that same thing and like I said it is only a 55 gallon tank. I believe I will just go with the one, and hopefully I will get a good push back into the tank to help with pushing the water around.. Not to mention it would mean drilling one less hole. [emoji106]I only have one but that is up to you. It depends on how many gallons you want coming out of your nozzle. You you want 825 or 2, 412.5