Hayward AquaRite Says No Flow With the Pump Running? How to Test the GLX-FLO-25 Flow Switch
Your pump is running, water is moving through the returns, and the salt system still insists there is no flow. It is one of the most common calls we get. Nine times out of ten the water is fine and the problem is the little sensor watching it, the Hayward GLX-FLO-25 flow switch.
Here is how to figure out whether the switch is actually bad before you buy anything.
What does the GLX-FLO-25 flow switch do?
It is a safety sensor. The GLX-FLO-25 sits in the return plumbing and tells the control box whether water is actually moving before it lets the cell make chlorine.
That matters because a salt cell energized in still water can build up gas and damage itself. So Hayward wired it as a hard stop. No signal from the flow switch means no chlorine production, no matter what the rest of the system thinks. It screws in with a 1/2 inch MPT thread and comes with a 25 foot cable that runs back to the control board.
Why is my AquaRite showing no flow when the pump is running?
Usually it is either real low flow or a failed sensor. Rule out the easy plumbing stuff first, because it takes five minutes and costs nothing.
- Dirty or clogged filter. High pressure on the gauge means less water actually reaching the return line.
- Full pump basket or skimmer basket choking suction.
- A valve turned partly closed, or a spa valve left in the wrong position.
- Air in the system from a low water level or a leaking pump lid o-ring.
- A variable speed pump running at too low an RPM. Bump it up and see if the light clears.
- The switch installed backward. There is a flow direction arrow on the body and it has to point the same way the water goes.
If none of that changes anything, it is time to test the GLX-FLO-25 itself.
How to test a Hayward GLX-FLO-25 flow switch
The quickest test is a temporary jumper at the control board. If jumping the two flow switch terminals makes the no flow condition disappear, the switch is bad.
- Kill power to the salt system at the breaker. Do not skip this.
- Open the control box and find the two terminals where the flow switch cable lands.
- Disconnect the two flow switch wires and connect a short piece of wire across those two terminals.
- Restore power with the pump running and watch the display.
- If the unit now reports normal flow and starts generating, the switch has failed. If it still says no flow, the problem is somewhere else, likely the board.
Test only. Take the jumper back out as soon as you know the answer. Leaving a salt system jumpered removes the protection that keeps the cell from firing in a dry pipe, and that is how people end up buying a cell instead of a $220 sensor.
You can also check it with a multimeter on continuity. Pull the switch out, set the meter to continuity, and touch the two conductors. With no water moving it should read open. Blow gently through the fitting or push the internal paddle and it should close. A switch that never closes, or one stuck closed, is done.
Signs the switch is bad and not the cell or the board
A few patterns point straight at the GLX-FLO-25:
- The no flow light comes and goes on its own with no change in pump speed or filter pressure.
- Filter pressure and return flow both look completely normal.
- The jumper test clears the fault instantly.
- The cable is cracked, chewed, sun rotted, or the terminals are green and corroded.
- The switch is more than five or six years old and lives in full sun.
If the cell itself were failing you would usually see low chlorine output or a cell diagnostic reading instead, not a flow error.
How to replace the GLX-FLO-25
It is a straightforward swap and most people do it themselves in under an hour.
- Turn off the pump and the salt system, then relieve pressure at the filter air relief valve.
- Unthread the old switch from its 1/2 inch tee in the return line.
- Wrap the new threads with a few turns of Teflon tape. Hand tight plus a small turn with a wrench is plenty. Overtightening cracks PVC fittings.
- Point the flow arrow in the direction of the water.
- Route the 25 foot cable back to the control box, keeping it clear of hot heater surfaces, and land the two wires on the same terminals you pulled them from.
- Power up, run the pump, and confirm the no flow light stays off.
Is the GLX-FLO-25 worth replacing?
Almost always yes. A flow switch is one of the cheapest parts in the whole salt system, and a bad one shuts down chlorine production entirely, which turns into an algae problem within a week or two of hot weather.
The exception is if your control box is also acting up, showing a dead display, random resets, or a fault that does not clear with a known good switch. In that case sort out the board first so you are not chasing the wrong part. The GLX-FLO-25 fits the common Hayward Goldline salt and automation setups that use the standard two wire flow input, so if that is what you pulled out, that is what goes back in.
Not sure this is the right part for your problem? Reach out and we will help you figure out exactly what you need before you spend money on the wrong thing.