Sta-Rite U9-371 drain cap o-ring for Cristal-Flo filtersSta-Rite Drain Cap O-Ring for Cristal-Flo Filter, U9-371 In stock$1099
Sta-Rite U9-371 drain cap o-ring for Cristal-Flo filters
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Sta-Rite Drain Cap O-Ring for Cristal-Flo Filter, U9-371

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$1099
In stock
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Quick overview

  • Genuine Sta-Rite Factory o-ring U9-371 rather than a hardware store ring in roughly the right size.
  • For Cristal-Flo filters Sold as the drain cap o-ring for the Sta-Rite Cristal-Flo filter.
  • Stops a weeping drain A drain cap that still drips after it is tight almost always has a flattened or cracked o-ring behind it.
  • Cheap part, real leak This is one of the least expensive parts on the filter and one of the most common sources of a puddle.
  • Change it while you are in there Worth swapping any time the filter is opened for a media change or a teardown.
  • Lubricate before fitting Use a pool rated silicone lubricant. Petroleum grease attacks o-ring rubber and shortens its life.
Full description and specifications ↓

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Product details

The Sta-Rite U9-371 is the drain cap o-ring for the Cristal-Flo filter. It is the seal that sits behind the drain cap at the base of the tank.

The part behind a leaking drain

Filter drains leak more often than any other point on the tank, and the o-ring is almost always the reason. Rubber that has flattened, hardened or split will not seal no matter how hard the cap is turned, and over tightening a cap to chase the drip is how caps get cracked.

Fitting it

Wipe the groove clean, give the new o-ring a light coat of silicone lubricant made for pool equipment, and hand tighten the cap. Keep petroleum grease away from it, because it swells and breaks down o-ring rubber. It is a part worth replacing on sight any time the filter is opened up.

Specifications
Brand Sta-Rite
Manufacturer part number U9-371
UPC 788379850968
Type Drain cap o-ring
Part type Pool filter part
Fits Sta-Rite Cristal-Flo filters
Shipping weight 0.01 lb
Ships Parcel

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Questions and answers

What people ask about this product, answered by our pool techs.

Where does this o-ring go?
Behind the drain cap at the bottom of the filter tank. It is the seal the cap compresses when you close the drain.
My drain cap is tight and still drips. Is this the part?
Almost certainly. Once the o-ring has flattened, hardened or split, tightening the cap harder does not restore the seal and usually cracks the cap instead.
Should I grease it?
Yes, lightly, with a silicone lubricant made for pool equipment. Do not use petroleum grease on o-rings because it swells and degrades the rubber.
Does the drain cap come with it?
No. This is the o-ring alone. The drain cap is a separate Sta-Rite part.
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