Hayward Star-Clear Plus Filter Leaking From the Lid? Check the Filter Head (CX1750B)
Water dripping or spraying from the top of a Hayward Star-Clear Plus cartridge filter almost always traces back to one of two parts: the lid o-ring or the filter head itself. The o-ring is the cheap fix. The filter head, part number CX1750B, is the fix when the o-ring didn't solve it. We see both at the counter every week, and telling them apart takes about five minutes.
Why is my Star-Clear Plus filter leaking at the lid?
The most common cause is an o-ring that has dried out, stretched, or picked up a nick. The second most common cause is a cracked or warped filter head, which is the dome-shaped top half of the tank that the clamp holds down.
Filter heads live a hard life. They sit in direct sun, they get hit with chlorine fumes every time you open the tank, and they hold pressure all season. Over the years the plastic gets brittle. A freeze with water still in the tank can crack one overnight. So can setting the head down on concrete or overtightening the air relief valve.
Quick test: is it the o-ring or the CX1750B head?
Swap or lube the o-ring first, since it costs a fraction of a new head. If the filter is still leaking after that, the head is your problem. Here's the order we'd check things in:
- Shut off the pump and open the air relief to bleed pressure.
- Remove the clamp and lift the head off. Pull the o-ring and look for flat spots, cracks, or debris stuck to it.
- Clean the o-ring groove, apply a thin coat of silicone-based lube, and reseat everything. Never use petroleum jelly on pool o-rings.
- Run the pump. If it still won't stop leaking, take the head off again and inspect it in good light.
Signs you need a new filter head
If you can see damage on the head, replace it. Don't try to glue or epoxy a pressurized tank part. Look for:
- Hairline cracks anywhere on the dome, especially around the clamp lip. Run a dry paper towel over the surface, since it will snag on cracks you can't see.
- Spider cracking or chalky, faded plastic. That's UV damage, and the part is near the end of its life even if it isn't leaking yet.
- Stripped or cracked threads where the air relief valve or pressure gauge screws in.
- A warped sealing edge. Set the head upside down on a flat surface and check for rocking.
- A leak that keeps coming back no matter how many o-rings you put in. That's the classic sign the sealing surface itself is gone.
How to replace the Star-Clear Plus filter head
This is one of the easier pool repairs, and most people do it themselves in under half an hour. No special tools needed beyond what came with the filter.
- Kill power to the pump and bleed off pressure at the air relief.
- Loosen and remove the band clamp, then lift off the old head.
- While you're in there, pull the cartridge and rinse it. You've already done the hard part of opening the tank.
- Fit a fresh, lubed o-ring, set the new CX1750B head on the tank body, and seat the clamp evenly. Snug it down without going crazy on the tightening.
- Move your pressure gauge and air relief valve over to the new head if they're in good shape.
- Restart the pump, open the air relief until water sprays out, then close it and check for drips.
Replace the head or buy a whole new filter?
If the tank body is in good shape, replacing just the CX1750B head is the smart move. A complete Star-Clear Plus filter costs a lot more than the head alone, and the bottom half of the tank rarely fails since it's not the part you're opening and closing all the time.
The math changes if the tank body is also cracked, or if the filter is decades old and the internals are crumbling. At that point put the money toward a new filter instead of chasing parts one at a time.
One more thing worth knowing: the CX1750B is the genuine Hayward part with the directional vent, made for compatible Star-Clear Plus models. Cheap knockoff heads exist, but on a part that holds pressure a few feet from where people swim, we'd stick with OEM.
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.