Balboa · VS / GS series (M7 heater)Fix soon

LF on a Balboa hot tub: persistent low flow

The system saw the HFL low-flow problem five times in 24 hours and has shut the heater off until you reset it. The tub runs but will not heat.

Also shown as: LOW FLOW, L F

Most likely causes

  1. 1Clogged or worn-out filtermost likely
  2. 2Low water levelcommon
  3. 3Air trapped in the plumbingcommon
  4. 4Failing pump or blocked impellerless common

What to try, in order

  1. Check the water level and top up if needed.
  2. Turn off power at the breaker and remove the filter. Clean it in a filter cleaner soak or swap in a new one.
  3. Make sure all jets are open and suction covers are clear of debris.
  4. Restore power and press any button to clear the LF message.
  5. Watch the tub for the next day. If HFL or LF returns with a clean filter, book a service visit.

LF questions

How do I reset LF on a Balboa hot tub?

Fix the flow problem first, then press any button on the topside panel. If the cause is still there, the code will return.

Is LF the same as FLO?

They point to the same kind of problem, which is poor water flow, but they come from different hardware. FLO comes from a pressure switch. LF comes from the two heater sensors on M7 systems.

Related codes

Balboa -- · Temperature not yet knownBalboa CHEK PH · Maintenance reminderBalboa CLN FLTR · Filter reminderBalboa CNFG FAIL · Configuration errorBalboa dr · Heater may be dryBalboa dry · Heater is dryBalboa Ecn · Economy modeBalboa FLO · Low water flow

General guidance. Follow your manufacturer's instructions; anything inside the control box is work for a licensed professional. Updated October 5, 2026.