Hot Tub Jets Not Working? Weak Flow, Airlocks and Pumps

Weak or dead hot tub jets usually come down to water flow: low water, dirty filters, closed valves or jet controls, or air trapped in the plumbing. Airlocks are especially common right after draining and refilling. Some causes are quick to fix yourself. A pump that hums but does nothing, runs hot or will not start needs a dealer or technician.

The short answer

Check the water level, clean or check the filters, and make sure the jets, air controls and valves are open. If the jets stopped after a refill, or the pump hums and jets work only in part of the spa, you probably have an airlock. Hudson Bay Spas says that in this case the pump needs priming, and warns never to let an unprimed pump run for more than 2 minutes. If the pump makes no sound at all, contact your dealer.

Key takeaways

Hot Spring lists low water, clogged filters and closed jet controls as likely causes of weak or surging jets.
Air in the pump or lines stops circulation, and running a pump with an airlock can damage it.
Closed slice valves can damage the spa if power is applied, according to Hudson Bay Spas.
Pumps that run hot, hum without moving water or make no sound need professional service.

Safety first

Hudson Bay Spas says to always turn the GFCI off before servicing or draining the spa.
Do not remove filters or baskets while the spa is running, and never run it with filters, lids or skimmers missing.
Keep hair, clothing and jewelry away from suction fittings. Public Health – Seattle & King County warns that injuries or deaths can occur when hair or a body part is trapped by suction from a drain or outlet whose cover is broken or removed. Replace broken covers before anyone uses the tub.

Weak jets

When the jets run but feel weak or surge, start with these checks, which appear in both Master Spas’ and Hot Spring’s troubleshooting guides:

Water level: Master Spas says to check that water is up to the minimum safe level. Low water lets the pump draw air.
Filters: clogged filters restrict flow. Hudson Bay Spas notes that debris and mineral build-up in the filter may affect jet performance and limit water flow. See hot tub filter cleaning.
Jets and air controls: many jets can be turned closed, and diverter or air controls can be shut. Master Spas says to make sure jets and air controls are open. Hot Spring mentions its Comfort Control lever as an example.
Pump running: make sure the pump is actually on and at the expected speed.

Airlocks after refilling

Hudson Bay Spas explains that pumps are designed to move water, not air. Air trapped in the pump or plumbing prevents circulation, and letting the pumps run with an airlock can destroy them. Hot Spring also lists an airlock created after filling the spa.

Signs of an airlock

Hudson Bay Spas says that if you hear a “humming” sound, the jets do not work, or the jets work only in part of the spa when you press the jets button, you likely have an airlock and need to prime the pump.

Clearing it

The method depends on your spa, so use your manual. As an example of one manufacturer’s method, Hudson Bay Spas describes bleeding air at the pump’s air release screw: loosen the screw until water begins to trickle, do not remove it, and tighten it once water trickles steadily. Hot Spring’s chart, for its spas, describes placing the hose down the main filter in the filter compartment and filling the spa completely to push the airlock out. Follow the power instructions in your manual for either method.

Preventing it

Hudson Bay Spas says filling the spa according to the manufacturer’s instructions and soaking new filters for 30 minutes before powering on helps prevent airlocks. If you are refilling, see how often to change hot tub water.

Closed valves

Many spas have slice valves (gate valves) near the equipment so parts can be serviced without draining. Hudson Bay Spas says these must be locked fully open before power is applied, and that applying power with them closed can damage the spa immediately. After any service or refill, confirm the valves are open before switching on.

No jets at all

Master Spas’ guide separates two situations:

You hear the pump trying: check that slice valves are open, prime the pump, and check that air controls are open.
You hear nothing: contact your dealer for service.

Hudson Bay Spas’ troubleshooting table adds simpler causes: the pump cycle may have ended (press the button again), or there may be a blockage in the filter area. It also lists “no power” at the pump connection in the control box, which is for a technician to check.

When to call a professional

The pump makes no sound, or hums but water does not move after priming.
The pump runs hot. Hudson Bay Spas lists dry running as a cause and says to call the dealer.
The GFCI trips, or anything involves the control box or wiring. King County notes hot tub electrical equipment should be wired to the National Electric Code and local codes.
The jets stay weak after the water, filter, valve and airlock checks.

FAQ

Why do only some of my jets work?

Some jets may be closed or on a different pump or diverter setting. If none of those apply and it happened after refilling, Hudson Bay Spas says jets working only in part of the spa can be a sign of an airlock.

Can foam or chemicals affect the jets?

Foam does not usually stop jets, but it is a sign of water quality issues. See hot tub foam.

Sources

Research checked October 1, 2026. We only claim hands-on testing when we’ve actually tested the product ourselves. Manufacturer guidance applies to the named products; follow the manuals and labels for your own equipment.