Astralpool Multiport Valve Shaft O-Ring 40mm & 50mm - CA & ECA Filters - 75905

Astralpool Multiport Valve Shaft O-Ring 40mm & 50mm - CA & ECA Filters - 75905

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• Shipped from VIC, NSW, WA, QLD

Genuine Astralpool o-ring for the diverter shaft of Astralpool 40mm and 50mm multiport valves. Astralpool lists it simply as the O-Ring, No. 10 on the parts diagrams for the 50mm 76053 valve (CA300, CA340, CA400 filters) and the 40mm 76036 valve (ECA550, ECA650 filters). It is also sold as the cover shaft o-ring, stem o-ring, diverter ring or back ring. It seals the shaft where it passes through the valve cover, which stops water weeping out around the handle.

Water weeping around the handle is the usual sign this o-ring has failed. Water at the rim of the cover is a different o-ring, and water running to waste while the valve is on Filter is usually the spider gasket. Use the rule below to match the leak to the part before you order.

The Handle or Rim Rule (rev. MPV-SHAFT-1.0)

1. With the pump running and the valve on Filter, dry the valve and watch where water first appears.
2. At the centre, around the handle and shaft: this shaft o-ring, 75905, is the usual fix. While the cover is off, check the spring washers and spring for wear.
3. At the rim, the seam where the cover bolts to the valve body: not this part. You need the cover o-ring, 75930 on the 50mm valve or 75919 on the 40mm valve.
4. Water running to waste, or showing in the sight glass, while on Filter: an internal leak, not this o-ring. Usually a worn spider gasket or a weak spring (see the table below).

Turn the pump off and release the pressure before you remove the valve cover.

Fitment

This o-ring suits the valve, not the filter. An older filter may carry a different valve, so check the valve as well as the filter model. Astralpool lists 75905 on these valves:

Astralpool's 2018-19 and 2019-20 catalogues also list 75905 as No. 10 on the 40mm multiport assembly for the EC filter.

Not listed on the Multiport Valve - Sep 09 - Current parts list. That list, in the same 2026 catalogue, shows a pair of o-rings, 75062, at No. 10 instead. If your valve is not a 76053 or 76036, match the part number on your valve's own diagram, or send us a photo of the valve and we will confirm which o-ring it takes.

Specifications

• Part number: 75905
• Astralpool description: O-Ring
• Also sold as: cover shaft o-ring, stem o-ring, diverter ring, back ring
• Diagram reference: No. 10 on the 50mm 76053 and 40mm 76036 multiport valve diagrams
• Quantity per valve: 1 (76053 parts list)
• Port sizes: 40mm and 50mm valves
• Next on the diagram: plastic spring washer 75907 (No. 11), metal spring washer 75928 (No. 12), spring 75912 (No. 13)
• Barcode: 9343609028534

Related Multiport Valve Parts

• Cover O-Ring, 50mm MPV - 75930
• Cover O-Ring, 40mm MPV - 75919
• Spider Gasket, 50mm MPV - 75929
• Spider Gasket, 40mm MPV, 128mm 4-spoke - 75916
• Spring, MPV - 75912
• Plastic Spring Washer, MPV - 75907
• Metal Spring Washer, MPV - 75928
• Diverter Stem O-Rings - 75062
• Multiport Valve 50mm, CA Series - 76053
• Multiport Valve 40mm, ECA Series - 76036

When to Replace

Replace it when water weeps from around the handle with the pump running, or when the old o-ring is flattened, cracked or hardened. Replacing it means taking the cover off the valve, so it is worth fitting a new one whenever the cover comes off for a spider gasket or spring service.

Frequently Asked Questions

Is 75905 the o-ring that seals the valve cover?
No. The cover (lid) o-ring is a separate part: 75930 on the 50mm 76053 valve and 75919 on the 40mm 76036 valve. 75905 is the small No. 10 o-ring on the diverter shaft.

Does the same o-ring fit the 40mm and 50mm valves?
Yes. Astralpool lists 75905 at No. 10 on both the 50mm 76053 and the 40mm 76036 multiport valves.

Which filters use it?
The 2026 Astralpool catalogue lists it for the CA300, CA340 and CA400 (50mm valve 76053) and the ECA550 and ECA650 (40mm valve 76036). Earlier catalogues also listed it on the 40mm multiport assembly for the EC filter.

Water is leaking from around my valve handle. Is this the part?
Usually. Water around the handle and shaft with the pump running is the usual sign of a worn shaft o-ring. Check the spring washers and spring while the cover is off. If the water is coming from the seam where the cover meets the valve body, you need the cover o-ring instead.

Water runs to waste while the valve is on Filter. Will this o-ring fix it?
No. That is an internal leak, usually a worn spider gasket (75929 on 50mm valves, 75916 on 40mm valves) or a weak spring (75912).

My valve diagram shows two o-rings at No. 10. Do I need 75905?
Not necessarily. Astralpool's Multiport Valve - Sep 09 - Current parts list shows a pair of o-rings, 75062, at No. 10 instead of 75905. Match the part number on your valve's own diagram, or send us a photo of the valve.

Is this a genuine Astralpool part?
Yes. We are an authorised Astralpool and Fluidra dealer and warranty agent, and this is the genuine Astralpool 75905.

Manufacturer Catalogues, Diagrams & Part Numbers: Need exploded views, spare part numbers, product numbers, diagrams, or more product information? See the manufacturer catalogues below. In the Astralpool Catalogue 2026 spare parts section for filters, this o-ring is on the 50mm Multiport with Gauge diagram (76053, page 82) and the 40mm Multiport Assembly diagram (76036, page 83).

• Astralpool Catalogue 2026 | Zodiac Catalogue 2026

Important Before Ordering: Please ensure you order correctly. Confirm this product is suitable before ordering. Use the catalogues above, seek professional assistance, or contact us with photos of your existing part, model details, serial numbers, and any labels.

As with all products, these must be diagnosed and fitted by a qualified and experienced person. This is a special-order item.

Common search terms: Astralpool 75905, 75905 o-ring, Astral MPV cover shaft o-ring, multiport valve stem o-ring, diverter shaft o-ring, back ring Astralpool MPV, 76053 o-ring, 76036 o-ring, CA300 CA340 CA400 multiport valve o-ring, ECA550 ECA650 multiport valve o-ring, Hurlcon CA ECA stem o-ring, WWDG SpaPro.