Hayward Salt System Stuck on No Flow? How to Test and Replace the GLX-FLO-25 Flow Switch
Your pump is running. Water is shooting out of the returns. And your Hayward salt system still says No Flow and refuses to make chlorine. We get this call all the time at the shop, and more often than not the fix is a little part called the Hayward GLX-FLO-25 flow switch.
The good news is that testing it takes about five minutes, and replacing it is one of the easier repairs you can do on a salt system. Here is how to figure out if the GLX-FLO-25 is your problem.
What does the No Flow light actually mean?
The No Flow indicator means the control board is not getting a closed signal from the flow switch. It does not necessarily mean water has stopped moving. The salt cell needs water passing through it to work safely, so when the board thinks flow has stopped, it shuts the cell down as a protection measure.
So there are really only two possibilities. Either you have a real flow problem, or the flow switch is not working and is telling the board a lie. Your job is to figure out which one it is before you spend any money.
First, rule out a real flow problem
Before you blame the switch, make sure water is actually moving the way it should. A partially blocked system can produce weak flow that is not enough to trip the switch closed.
- Empty the pump and skimmer baskets
- Clean or backwash your filter if the pressure gauge is reading high
- Check that all valves feeding the salt cell are fully open
- Look for air bubbles in the pump lid, which point to a suction leak
- If you run a variable speed pump, bump the speed up. Low RPM settings sometimes do not push enough water to close the switch
If flow looks strong and the No Flow light stays on, keep going. The switch is now the prime suspect.
How to test a Hayward GLX-FLO-25 flow switch
The quickest test is a continuity check with a basic multimeter. With the pump off, unplug the flow switch cable from the control board and touch your meter leads to the connector terminals. You should see an open circuit. Then have someone turn the pump on. With good flow, the paddle inside the switch closes and your meter should show continuity.
If the switch stays open with the pump running at full speed, it has failed and needs to be replaced. If it shows continuity but the board still says No Flow, inspect the cable along its full length for cuts or chew marks, and check the connector pins for corrosion. A damaged cable is a failed switch for all practical purposes, since the GLX-FLO-25 comes as one sealed unit with its 25 foot cable attached.
One more thing to look at: pull the switch out and check the paddle itself. Scale buildup or debris can jam it so it never closes, even in strong flow. Sometimes a gentle cleaning buys you another season, but a sticky paddle usually comes back.
Which Hayward systems is the GLX-FLO-25 compatible with?
The GLX-FLO-25 is the standard flow switch used across Hayward and Goldline salt chlorination and automation systems, including the AquaRite, AquaRite Pro, AquaLogic, and ProLogic. It has a half inch MPT thread and a 25 foot cable, which gives you plenty of length to reach from the plumbing to the control box on most equipment pads.
If you are not sure yours matches, look at the tee fitting where your current switch sits. The GLX-FLO-25 threads into the same half inch port that Hayward has used on these systems for years.
How to replace the flow switch
Replacement is simple. Plan on 15 to 20 minutes.
- Kill power to the pump and the salt system at the breaker
- Unplug the old switch cable from the control board
- Unthread the old switch from its tee fitting
- Wrap the new switch threads with a few turns of thread seal tape
- Thread it in so the arrow on the switch body points in the direction of water flow. This matters. Backwards installation is the most common mistake we see
- Route the cable back to the board, plug it in, and restore power
Fire the pump up and the No Flow light should clear within a few seconds. If it does not, and you have confirmed strong flow and a correctly installed switch, the problem may be on the board side, and that is worth a phone call before you buy anything else.
Is it worth fixing?
Absolutely. A failed flow switch means zero chlorine production, and a week of no chlorine in summer heat turns into an algae problem fast. Compared to the cost of a new control board or a green pool cleanup, the GLX-FLO-25 is a cheap fix that gets your salt system working again the same day it arrives.
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.