Why Does My Hot Tub Say FLO?

If your hot tub is displaying a FLO or flow error, it means the heater has detected low or restricted water flow.

Your heater needs water moving through it to operate safely. If there isn’t enough flow, the heater won’t work and the FLO error may appear.

Here are the first things I would check.

1. Make Sure the Pump Is Running

First, make sure your pump is actually running.

If the pump isn’t running, there’s no water flowing through the heater. That alone can cause the FLO error to appear because the heater will not operate without adequate water flow.

If the pump is running normally, check the filter next.

2. Check for a Dirty Filter

The most common reason for a FLO error is a dirty filter.

A clogged or dirty filter restricts the amount of water moving through the system. Even though the pump may be running, the heater may not be getting enough water flow.

If you have a portable hot tub, remove the filter and reset the breaker. Then check to see if the FLO error goes away.

If it does, you’ve found the problem.

Clean the filter thoroughly or replace it if necessary before putting it back into the hot tub.

What If You Have a Sand Filter?

If your spa or pool system uses a sand filter, backwash the filter to clean it.

Once you’ve finished backwashing, turn the pump back on and check to see whether the FLO error has cleared.

Still Seeing FLO?

If the pump is running and cleaning or removing the filter doesn’t correct the FLO error, there may be another restriction or equipment issue affecting water flow.

At that point, it may be time to have the system inspected by a pool and spa professional.