Hot tub pumps can become noisy when not working properly. Since hot tub pumps only last about six to eight years, loud noises produced from hot tub pumps means it's time to either repair or replace the pump. Any loud noises protruding from the pump should be promptly addressed before the pump fails and damages other parts of the hot tub, such as the heater. Loud noises can also come from the spa motor, which is an internal problem you should repair promptly.
Disconnect the electrical power, and remove the spa's access panel for safety reasons. If you have slice valves installed on either side of the pump, close them. If you don't have these valves, drain the hot tub.
Inspect the hot tub pump to see if it's hot, and find out if the pump has bad bearings caused by a leaking seal shaft. If this is the case, your pump is not turning freely and you are wasting money.
Determine if your hot tub pump has become noisy due to no or low water flow. Clean or replace your filters, if necessary, and check if the pressure switch is clogged. If you still have no or low water flow, check both the circulation and filter pumps.
Contact a spa professional in your area to diagnose the problem of your pump, and either repair it or install a new one. Trying to repair these kinds of problems with your hot tub can be dangerous and could even damage your hot tub.