Understanding Flow Condition Errors on Spa & Hot Tub Systems
If you own a spa or hot tub, chances are you’ve encountered the dreaded Flow Condition, FLO, or Low Flow error on your Gecko touchpad or Balboa keypad.
This is one of the most common issues spa owners face — and fortunately, one of the most preventable.
A Flow Condition error simply means:
Modern spa systems are designed with built‑in safety sensors inside the heater tube. If the system detects insufficient flow, it will shut down the heater to prevent overheating or damage.
Let’s break down the real causes and how to fix them.
🔧 1. Clogged or Dirty Filter (Most Common Cause)
Inside the heater tube is a flow sensor that measures water movement.
If your filter is clogged, dirty, or overdue for replacement, it restricts water flow.
When the flow drops below the required level:
• The sensor cannot detect proper flow
• The heater will not activate
• The system displays a Flow Condition / FLO error
How to fix it:
• Remove the filter and run the spa without it for 1–2 minutes
• If the error disappears, the filter is the culprit
• Clean or replace the filter immediately
This is the #1 cause of flow errors in both Gecko and Balboa systems.
🔧 2. Airlock in the Plumbing (Very Common After Refilling)
This is a major issue that many spa owners don’t know about.
When a spa is drained and refilled incorrectly, air becomes trapped inside the plumbing, especially inside the heater tube.
The flow sensor then detects half water, half air, which is not enough to activate the heater.
Why airlocks happen:
Most customers refill the spa by placing the hose inside the spa shell.
This pushes air into the plumbing lines.
Correct way to refill:
Insert the hose inside the filter housing so water flows directly into the plumbing and pushes air out.
Symptoms of an airlock:
• Flow error immediately after refilling
• Pump runs but no water movement
• Gurgling or bubbling noises
• Heater not activating
How to fix an airlock:
• Loosen the union on the pump slightly to release trapped air
• Run the pump on high speed for 30–60 seconds
• Refill through the filter housing next time
🔧 3. Faulty Circulation Pump
Your circulation pump is responsible for pushing water through:
• The filter
• The heater tube
• The flow sensor
If the pump is weak, failing, or not running at all, the system will not detect enough flow.
Signs of a failing circulation pump:
• Pump is hot to the touch
• Low water movement in the spa
• Pump makes humming or grinding noises
• Flow error appears randomly
Fix:
• Check for blockages
• Ensure the pump is receiving power
• Replace the circulation pump if necessary
🔧 4. Plumbing Leak Causing Loss of Pressure
Even a small leak can reduce water pressure enough to trigger a flow error.
Signs of a leak affecting flow:
• Water level drops over time
• Damp or wet areas under the spa
• Air bubbles entering the system
• Flow error appears intermittently
Fix:
• Identify and repair the leak
• Top up water level
• Bleed air from the system
🔧 5. Faulty Flow Sensor or Pressure Switch
If all other causes are eliminated, the flow sensor itself may be defective.
Symptoms:
• Error persists even with filter removed
• Pump is running normally
• No airlock present
• Heater tube is full of water
Fix:
• Replace the flow sensor (Gecko)
• Replace the pressure switch (Balboa)
🛠️ How to Prevent Flow Condition Errors
• Clean your filter every 2–4 weeks
• Replace filters every 12 months
• Always refill through the filter housing
• Keep water level above the skimmer
• Inspect circulation pump regularly
• Check for leaks around unions and fittings
Prevention is always cheaper than repair.
FAQ Section
Why does my spa show a FLO error?
Because the heater is not receiving enough water flow to operate safely.
Can I run my spa with a flow error?
No — the heater will not activate, and running pumps dry can cause damage.
Is a flow error dangerous?
The error itself is a safety feature. It prevents overheating and protects the heater.
Does a flow error mean my heater is broken?
Not necessarily. Most of the time, the issue is filter, airlock, or pump related.
• Replacement filters https://ecospaparts.com.au/search?q=filter&type=product%2Carticle%2Cpage&options%5Bprefix%5D=last
• Circulation pumps https://ecospaparts.com.au/search?q=circulation+pump&type=product%2Carticle%2Cpage&options%5Bprefix%5D=last
• Heaters https://ecospaparts.com.au/search?q=heater&type=product%2Carticle%2Cpage&options%5Bprefix%5D=last
• Spa chemicals https://ecospaparts.com.au/search?q=chemicals&type=product%2Carticle%2Cpage&options%5Bprefix%5D=last
• Maintenance kits https://ecospaparts.com.au/search?q=maintenance+kit&type=product%2Carticle%2Cpage&options%5Bprefix%5D=last