If your pump is above the water level of the pool, it will need to prime after the strainer has been opened and air has been let into the system. To do this, the pump has to pump out the air and suck up the water. Most pool pumps are self-priming up to about 500 mm or 1,000 mm when new, but the internal priming seals wear out with time and the priming height reduces with age. This is particularly so if you add chemicals to the skimmer box. Chemicals are always better distributed around the pool rather than added to eth skimmer box.
Pooled Energy systems will run a priming sequence each time they start the pump, just in case you have opened the strainer and let air in. This runs for about 2 minutes and if the pump has not primed at that stage, it will shut down automatically.
If your pump is more than 1 metre above the water surface, you may need a special high-lift pump for it to prime. You may also need non-return valves in the plumbing to minimise the air in the inlet pipes. These need to be correctly installed and, in some cases, non-return valves with strong springs, can prevent, rather than assist priming.
If you do open the pump lid, it is a good idea to fill the leaf basket as full as possible with water. If your system does not prime, and the strainers and skimmers are clean, you may need a new pump.
If your system is having trouble priming, please clean the system, add water to the leaf basket and run the pump filter in manual using the Pool App.