A pond fountain pump is commonly used for circulating water and checking algae growth in water bodies. So, you need to choose one of the best fountain pumps with great care. First and foremost, determine the size of the pump you need. Water needs to be circulated through the filter at least once every hour if there is fish. So, if you have 1000-gallon pond, look for a pump which can produce a minimum of 1000 gallons per hour. (This is not the case for large ponds, which don't require as much circulation.
If there are fish in your pond, you will have to pay attention to filtration. In the majority of pond setups, the main pump drives water through the filtration system. So, more filtration will be needed. One wise thing which you can do is to double the flow if there is fish in your pond.