Sta-Rite U9-301 gray tank o-ring for Posi-Flo cartridge filtersSta-Rite Posi-Flo Tank O-Ring, Gray, U9-301 In stock$1399
Sta-Rite U9-301 gray tank o-ring for Posi-Flo cartridge filters
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Sta-Rite Posi-Flo Tank O-Ring, Gray, U9-301

Ask a questionMPN U9-301
$1399
In stock
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Quick overview

  • Genuine Sta-Rite Factory part U9-301, not a generic ring cut to a nominal size.
  • Posi-Flo cartridge filters The tank o-ring for the Sta-Rite Posi-Flo series.
  • Gray Supplied in the gray compound Sta-Rite uses for this seal.
  • Stops the classic lid leak Water weeping from the seam between the filter lid and the body is almost always this ring.
  • Replace it whenever the tank is open The ring takes a set once it has been compressed, so a cleaning is the right time to fit a fresh one.
  • Not the Posi-Flo II ring The PTM and Posi-Flo II series use a different Sta-Rite o-ring, so check which filter you have.
Full description and specifications ↓

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Product details

The Sta-Rite U9-301 is the gray tank o-ring for Posi-Flo cartridge filters. It is the genuine Sta-Rite part.

What it seals

This ring sits in the groove where the filter lid meets the tank body. Under pressure it is the only thing between the filtered water and the equipment pad, so when it hardens, flattens or picks up a nick, the filter starts to weep at the seam. Owners often chase the clamp or the lid before realising the ring is the whole problem.

Fitting it

Clean the groove out before the new ring goes in, because grit trapped under an o-ring will leak just as reliably as a worn one. Use a silicone o-ring lubricant, never a petroleum grease, and keep a spare on the shelf so a cleaning never turns into a trip to the store.

Check the series

Sta-Rite uses a different o-ring on the Posi-Flo II and PTM filters. Match the series on your tank label rather than the shape of the lid.

Specifications
Brand Sta-Rite
Manufacturer part number U9-301
UPC 788379850937
Type Tank o-ring
Color Gray
Fits Sta-Rite Posi-Flo cartridge filters
Shipping weight 0.1 lb
Ships Parcel

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Questions and answers

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

Which filter does this o-ring fit?
The Sta-Rite Posi-Flo cartridge filter. It is the tank o-ring, the seal between the lid and the tank body.
Will it fit a Posi-Flo II or a PTM filter?
No. Those filters take a different Sta-Rite o-ring, so confirm the exact series on your tank label before ordering.
Do I need to lubricate it?
Use a silicone based o-ring lubricant. Petroleum grease attacks the rubber and shortens the life of the seal.
My filter leaks at the lid. Is this the part?
Almost certainly. Water weeping from the joint between the lid and the tank is the standard symptom of a flattened, nicked or dried out tank o-ring.
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