Hot tubs require draining at the end of each season to keep the pump and jets safe from damage during the winter. You can take precautions when it comes time to refill the tub to reduce the chance of problems and provide a clean environment for bathers.
You can take steps to address an air lock during filling before you take your first dip.
Fill the Pool
The easiest way to fill your hot tub is with your garden hose. Run the hose for a few seconds to clear stagnant water out of the pipe.
Place the hose in the tub and let it fill until the water level is halfway up the skimmer, the small plastic pocket on the side of the pool that collects leaves and other debris. All the jets should be covered when the pool is full.
Test for an Air Lock
Test the pool's pump system to detect an air lock. Turn on the pump; water should come out of the jets if everything is normal.
If nothing happens, you have an air lock. Shut down the pump and turn off the power at the circuit breaker, wait 10 seconds and try again by turning the circuit breaker and pump back on.
Solution: Bleeder Valve
Bleeder valves fitted to some hot tubs release trapped air from the pipes. Open the valve near the filter cartridge to release trapped air before turning the power back on.
Switch the jets on one by one, if possible, or all at the same time to clear the remaining air from the pipes.
Solution: Remove the Filter
The filter cartridge traps debris in the water and is sometimes the cause of an air lock. Turn off the power, take the filter cartridge out of the system and run the pumps to clear trapped air.
If the air lock was caused by the filter, it should clear as a result of this step. The location of the filter varies by model; it is usually found beneath the hot tub's service hatch, accessible by loosening its screws.
Solution: Loosen the Union Nut
Persistent air locks sometimes need to be cleared from the pipes manually. Run the pump for a few seconds to identify which jet is blocked and turn the power off.
Take off the access cover off the pump and use an adjustable wrench to carefully loosen the union nut connecting the pipe to the pump. A half or quarter turn is usually all that's necessary for the trapped air to hiss out.
Avoid loosening the union nut any more than a full turn; water could leak out and cause a mess. Once the air has escaped, tighten the nut, replace the cover and turn the power back on.