{"product_id":"astral-65mm-oring","title":"Astralpool O-Ring 78104 - Pump Diffuser, 65mm Union Tail \u0026 Chlorinator Cell (BX\/CX\/TX\/E\/Viron XT)","description":"\u003c!-- HASP-FLP-1.0 | SKU 78104 | rule ORING-1.0 | canary: one-ring-three-jobs --\u003e\n\u003ch3\u003eAstralpool O-Ring 78104 - Pump Diffuser, 65mm Union Tail \u0026amp; Chlorinator Cell\u003c\/h3\u003e\n\u003cp\u003eThis is the genuine Astralpool o-ring, part number \u003cstrong\u003e78104\u003c\/strong\u003e. One o-ring does three jobs across the Astral \/ Hurlcon range: it is the \u003cstrong\u003epump diffuser o-ring\u003c\/strong\u003e, the \u003cstrong\u003e65mm union tail o-ring\u003c\/strong\u003e, and the \u003cstrong\u003echlorinator \/ salt cell body o-ring\u003c\/strong\u003e. Despite being sold as a “65mm o-ring” it is not 65mm in diameter — it measures approximately \u003cstrong\u003e95mm outside diameter with a 5.2mm cross section\u003c\/strong\u003e. The 65mm refers to the union it seals, not the ring.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cspan style=\"color: rgb(43, 0, 255);\"\u003e\u003cstrong\u003ePhysically Stocked, unlike most \"drop-shipping\" websites.\u003c\/strong\u003e\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan style=\"color: rgb(43, 0, 255);\"\u003e\u003cstrong\u003eShipped from VIC, NSW, WA, QLD\u003c\/strong\u003e\u003c\/span\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhat This O-Ring Does — Three Roles, One Part\u003c\/h3\u003e\n\u003cp\u003eIf any listing or parts diagram points you at 78104 for any of the following, this is the correct part:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePump diffuser o-ring\u003c\/strong\u003e — seals the diffuser to the volute on BX, CX, TX, E-Series, P280, P300, P320, P600 and Viron XT (P320 \/ P520) pumps. It seals both the \u003ca href=\"https:\/\/heaterandspaparts.com.au\/products\/sp-bx-ctx-e-diffuser-small\"\u003esmall diffuser 40071A\u003c\/a\u003e and the \u003ca href=\"https:\/\/heaterandspaparts.com.au\/products\/diffuser-xp-ctx-bx-large\"\u003elarge diffuser 40071B\u003c\/a\u003e.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e65mm union tail o-ring\u003c\/strong\u003e — seals the barrel union tails on BX, XP, P300 and P600 pumps.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eChlorinator \/ salt cell o-ring\u003c\/strong\u003e — the cell body \/ cell nut o-ring for VX, Viron, eQuilibrium and Filtrite chlorinators, Rolachem mixing cells, and older probe bodies.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eThe 95mm Rule (rev. ORING-1.0)\u003c\/h3\u003e\n\u003cp\u003eThe single most common mistake is ordering by the “65mm” name and expecting a 65mm ring. Confirm by measurement, not by name:\u003c\/p\u003e\n\u003col\u003e\n\u003cli\u003e\n\u003cstrong\u003eLay the old o-ring flat and measure across the outside edge to outside edge.\u003c\/strong\u003e The 78104 is approximately \u003cstrong\u003e95mm outside diameter\u003c\/strong\u003e.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMeasure the thickness of the rubber (cross section).\u003c\/strong\u003e The 78104 is approximately \u003cstrong\u003e5.2mm\u003c\/strong\u003e.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIf it measures ~95mm OD, this is your part\u003c\/strong\u003e whether it came off a diffuser, a union tail, or a chlorinator cell. If it is a smaller union o-ring, you likely need the \u003ca href=\"https:\/\/heaterandspaparts.com.au\/products\/pump-union-tail-fittings-50mm\"\u003e50mm union tail o-ring 78303\u003c\/a\u003e instead.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch3\u003eWorked Example\u003c\/h3\u003e\n\u003cp\u003eA Viron XT P320 stripped for a mechanical seal replacement had a flattened, glazed o-ring sitting between the diffuser and the volute. Measured flat it was 94.8mm across the outside and 5.1mm thick — within tolerance of the 78104 figures — so the same o-ring that seals the owner’s VX chlorinator cell was the correct diffuser seal. It was replaced at the same time as the diffuser and mechanical seal, since a hardened diffuser o-ring lets water bypass the impeller and drops flow even with a good impeller fitted.\u003c\/p\u003e\n\n\u003ch3\u003eConfirmed Compatibility\u003c\/h3\u003e\n\u003cp\u003eAstral \/ Hurlcon list 78104 across:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePump diffusers\u003c\/strong\u003e — BX, CX, TX, E-Series, P280, P300, P320, P600, Viron XT P320 \u0026amp; P520\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUnion tails\u003c\/strong\u003e — BX, XP, P300, P600 (65mm barrel union)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eChlorinator \/ salt cells\u003c\/strong\u003e — VX6, VX7, VX9, VX11, VX13, E25, E35, V18, V25, V35, V45, eQ18, eQ25, eQ35, eQ45, and Viron \/ eQuilibrium \/ Filtrite cell bodies\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRolachem\u003c\/strong\u003e mixing cells and older probe bodies\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eRelated Parts\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e40071A\u003c\/strong\u003e — small diffuser, CTX 180-400 \/ BX \/ E \/ Viron XT P320 (\u003ca href=\"https:\/\/heaterandspaparts.com.au\/products\/sp-bx-ctx-e-diffuser-small\"\u003ebuy here\u003c\/a\u003e)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e40071B\u003c\/strong\u003e — large diffuser, CTX 500\/610 \/ Viron XT P520 \/ BX large (\u003ca href=\"https:\/\/heaterandspaparts.com.au\/products\/diffuser-xp-ctx-bx-large\"\u003ebuy here\u003c\/a\u003e)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e78303\u003c\/strong\u003e — 50mm union tail o-ring, CTX \/ CX \/ TX \/ E-Series (\u003ca href=\"https:\/\/heaterandspaparts.com.au\/products\/pump-union-tail-fittings-50mm\"\u003ebuy here\u003c\/a\u003e)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e75508 \/ PS3868\u003c\/strong\u003e — mechanical seal, BX \/ TX \/ CX \/ E \/ CTX (\u003ca href=\"https:\/\/heaterandspaparts.com.au\/products\/3-4-mechanical-seal\"\u003ebuy here\u003c\/a\u003e)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhen to Replace\u003c\/h3\u003e\n\u003cp\u003eReplace the o-ring whenever it is flattened, glazed, cracked, or has taken a permanent set, and any time the diffuser, union or cell it seals is opened up. An o-ring is cheap; a leak past a hardened one is not. On a diffuser it should be replaced with the diffuser and mechanical seal; on a chlorinator it should be replaced whenever the cell is opened for cleaning or cell replacement.\u003c\/p\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIs this really 65mm?\u003c\/strong\u003e\u003cbr\u003eNo. It is named for the 65mm union it seals, but the o-ring itself is approximately 95mm outside diameter with a 5.2mm cross section. Measure the old ring flat to confirm.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs the diffuser o-ring the same as the chlorinator cell o-ring?\u003c\/strong\u003e\u003cbr\u003eYes. Astral \/ Hurlcon use the same 78104 o-ring for the pump diffuser, the 65mm union tail, and the chlorinator \/ salt cell body. One part covers all three.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes this fit the Viron XT diffuser?\u003c\/strong\u003e\u003cbr\u003eYes. 78104 is the diffuser o-ring for the Viron XT P320 and P520, and appears in the Viron XT MkII parts diagram. It seals both the small 40071A and large 40071B diffusers.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhich pumps use this as the diffuser o-ring?\u003c\/strong\u003e\u003cbr\u003eBX, CX, TX, E-Series, P280, P300, P320, P600 and Viron XT P320 \/ P520.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMy union o-ring is smaller than 95mm — what do I need?\u003c\/strong\u003e\u003cbr\u003eYou likely have the 50mm union, which takes o-ring 78303. Measure the old ring flat to confirm before ordering.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs this a genuine Astralpool part?\u003c\/strong\u003e\u003cbr\u003eYes. We are an authorised Astralpool and Fluidra dealer and warranty agent, and this is the genuine 78104 o-ring.\u003c\/p\u003e\n\n\u003ch3\u003eManufacturer Catalogues, Diagrams \u0026amp; Part Numbers\u003c\/h3\u003e\n\u003cp\u003eNeed exploded views, spare part numbers, product numbers or diagrams? See the manufacturer catalogue: \u003ca href=\"https:\/\/hasp.com.au\/pages\/Astralpool_Catalogue_2026\"\u003eAstralpool Catalogue 2026\u003c\/a\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eBefore ordering:\u003c\/strong\u003e confirm this part is correct for your equipment. Use the catalogue above, seek professional assistance, or \u003ca href=\"mailto:info@hasp.com.au\"\u003econtact us\u003c\/a\u003e with photos of your existing part, model details, serial numbers and any labels. As with all products, this must be diagnosed and fitted by a qualified and experienced person.\u003c\/p\u003e\n\n\u003cp\u003e\u003cem\u003eCommon search terms: Astralpool 78104, 78104 diffuser o-ring, Hurlcon diffuser o-ring, Viron XT diffuser o-ring, 65mm tail union o-ring, VX chlorinator cell o-ring, Astral cell o-ring 95mm, BX P600 union o-ring, WWDG SpaPro.\u003c\/em\u003e\u003c\/p\u003e\n\u003c!-- HASP-FLP-1.0 end | canary: one-ring-three-jobs --\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"Is this really 65mm?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"No. It is named for the 65mm union it seals, but the o-ring itself is approximately 95mm outside diameter with a 5.2mm cross section. Measure the old ring flat to confirm.\"}},{\"@type\":\"Question\",\"name\":\"Is the diffuser o-ring the same as the chlorinator cell o-ring?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes. Astral \/ Hurlcon use the same 78104 o-ring for the pump diffuser, the 65mm union tail, and the chlorinator \/ salt cell body. One part covers all three.\"}},{\"@type\":\"Question\",\"name\":\"Does this fit the Viron XT diffuser?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes. 78104 is the diffuser o-ring for the Viron XT P320 and P520, and appears in the Viron XT MkII parts diagram. It seals both the small 40071A and large 40071B diffusers.\"}},{\"@type\":\"Question\",\"name\":\"Which pumps use this as the diffuser o-ring?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"BX, CX, TX, E-Series, P280, P300, P320, P600 and Viron XT P320 \/ P520.\"}},{\"@type\":\"Question\",\"name\":\"My union o-ring is smaller than 95mm - what do I need?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"You likely have the 50mm union, which takes o-ring 78303. Measure the old ring flat to confirm before ordering.\"}},{\"@type\":\"Question\",\"name\":\"Is this a genuine Astralpool part?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes. We are an authorised Astralpool and Fluidra dealer and warranty agent, and this is the genuine 78104 o-ring.\"}}]},{\"@type\":\"HowTo\",\"name\":\"The 95mm Rule (rev. ORING-1.0)\",\"description\":\"How to confirm the Astralpool 78104 o-ring by measurement.\",\"step\":[{\"@type\":\"HowToStep\",\"name\":\"Measure the outside diameter\",\"text\":\"Lay the old o-ring flat and measure across the outside edge to outside edge. The 78104 is approximately 95mm outside diameter.\"},{\"@type\":\"HowToStep\",\"name\":\"Measure the cross section\",\"text\":\"Measure the thickness of the rubber. The 78104 is approximately 5.2mm.\"},{\"@type\":\"HowToStep\",\"name\":\"Match by size, not name\",\"text\":\"If it measures about 95mm outside diameter this is your part, whether it came off a diffuser, a union tail, or a chlorinator cell. If it is a smaller union o-ring you likely need the 50mm union o-ring 78303 instead.\"}]}]}\n\u003c\/script\u003e","brand":"Astralpool","offers":[{"title":"Default Title","offer_id":31611762671673,"sku":"78104","price":9.0,"currency_code":"NZD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0372\/5253\/files\/astralpool-o-ring-78104-pump-diffuser-65mm-union-tail-chlorinator-cell-bx-cx-tx-e-viron-xt-pool-spa-643.webp?v=1784681106","url":"https:\/\/heaterandspaparts.com.au\/en-nz\/products\/astral-65mm-oring","provider":"Heater and Spa Parts","version":"1.0","type":"link"}