1. Choose the theory of the pump. BLDC PUMP is centrifugal pump, can not self priming.
2. Confirm the type of power, AC or DC? AC pump is cheap but not safe and not good quality. DC pump is slightly expensive because of its cost of electronic components. Meanwhile, only DC pump can achieve complex functions, such as speed control, smart program. You need to consider that which is more important for you, the cost or the performance?
3. Consider your requirements of the head and flow rate; this is the most important thing during you choosing the water pumps. In general, all pumps will be marked a max head and a max flow rate. Please note: it does not mean that the pump can achieve the max head and max flow rate at the same time. Usually, you need choose a higher head than your actual needs, because when the pump achieved its max head its flow rate will be zero. Our head-flow graph will be helpful for your decision.
4. Consider the appearance of pump, the size and direction of the input and output, whether need threaded connection? If you really need a customized appearance, we can do it, but it is not cheap. So I suggest you try to choose a model we have it in stock.
5. When you are considering these issues above, you also need to consider other things: pump's working environment, temperature, media, whether need program control, speed control, time control, motion control, pressure control and flow control etc. More capability will cost more; you need to consider whether you really need!