Air pumps are perfect for getting oxygen into a pond, especially for bigger fish, like Koi and Goldfish, that need that little extra oxygen. You can never have too much oxygen and it will only help with any biological filtration you have and also aid in fish health. Air pumps are a good idea for anyone wanting to turn off their noisy waterfall’s at night, so that your fish still get that needed aeration, especially seeing as the lowest time for oxygen in a pond is twelve o’clock at night till six in the morning.