Hot tub pumps typically are the hardest working unit in a hot tub. Circulation pumps move water through the tub for filtering and heating purposes.
A few simple diagnostic steps can help you figure out why the pump does not turn back on.
After refilling the hot tub, make sure you prime the pump. To accomplish this, you should open the bleeder valve that lets air escape from the pipes.
Some hot tubs may require you to shut off the power to the spa and turn it back on after a few moments to starting the priming process.
Other Corrective Actions
Check all water intake valves to ensure no obstructions exist after refilling the tub. You also may need to check the filter cartridge to ensure the filter is free from blockages and installed correctly.
Always review your hot tub before draining and refilling. Knowing how your hot tub works will help you understand what can or will happen when draining and refilling the tub.
Additionally, make sure the pump is working before you drain the tub.