Astralpool O-Ring, Tank Lid Green - ECA550, ECA650 Filter - 7201750057
Astralpool O-Ring, Tank Lid Green - ECA550, ECA650 Filter - 7201750057 is temporarily out of stock and will ship as soon as it's available.
Don't Guess - Ask Us!
Don't Guess - Ask Us!
Not sure if it’s the right part? Send us a message and a photo of what you’re replacing, or what you need, and we’ll help make sure you get the right part the first time.
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Delivery and Shipping Info*
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Astralpool O-Ring, Tank Lid Green - ECA550, ECA650 Filter - 7201750057
Astralpool O-Ring, Tank Lid Green - ECA550, ECA650 Filter - 7201750057 is temporarily out of stock and will ship as soon as it's available.
Astralpool O-Ring, Tank Lid Green - ECA550, ECA650 Filter - 7201750057
- We keep these physically in stock for fast shipping or local pick-up, unlike most drop-shipping websites.
- Shipped from VIC, NSW, WA, QLD
Genuine green tank lid O-ring for Astralpool ECA series sand filters. This is the seal between the filter tank and the lid / multiport valve, and it is the usual cause of a joint that weeps with the clamp band correctly tightened.
ECA or CA? They Use Different O-Rings
- ECA series - this O-ring, 7201750057.
- CA / Cantabric series - 7211820060.
If you are unsure which filter you have, send us a photo of the tank label and we will confirm.
When to Replace
- Water weeping from the lid joint with the clamp band sound and tight.
- O-ring visibly flattened, split, hardened or taking a permanent set.
- Any time the tank is opened for media replacement - cheap insurance while you are in there.
Specifications
- Part number: 7201750057
- Fits: Astralpool ECA550, ECA650
- Colour: green
- Function: tank to lid / valve seal
- Barcode: 9343609002619
Related ECA Filter Parts
- Multiport Valve 40mm, ECA550 / ECA650 - 76036
- Clamp Band ECA Complete - 77730
- Clamp Band Bolt, Nut & Allen Key Kit - 78399
- Lateral Hub, ECA & CA Media Filter - 77712
- Laterals 175mm, Pair - 77756
- Drain Plug Cap, CA / ECA - 77717
- Component Bag 40mm ECA Multiport - 78355
Frequently Asked Questions
Will this O-ring fit a CA or Cantabric filter?
No. CA and Cantabric filters use O-ring 7211820060. This one suits the ECA series.
Should I lubricate the O-ring on fitting?
Use a silicone-based lubricant suitable for pool equipment. Do not use petroleum-based grease, which degrades the rubber.
Manufacturer Catalogues, Diagrams & Part Numbers: Need exploded views, spare part numbers, product numbers, diagrams, or more product information? See the manufacturer catalogues below.
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.
To the layperson, plumbing sizes and their names can be confusing due to the nominal sizes and naming conventions used.
This is not something we made up. Plumbers and manufacturers have used nominal (meaning ‘by name only’) sizing for decades.
Simply put, in plumbing, named sizes are often not the actual measurements of the pipe, fitting, or part. A PVC pipe called “50mm” or “2"” does not measure 50 mm anywhere. Instead, it follows nominal sizing, an internationally-standardised naming system.
Almost all fittings we use in the pool & spa industry use “pressure PVC” pipe & fittings. Do not confuse with “DWV” or other pipe & fittings and their names and sizes.
Use the Outside Diameter (OD) to check your pipe against fittings. Below is a quick reference for common spa & pool pipe sizes:
| Imperial Name | Metric Name | Pipe Diameter (OD) |
|---|---|---|
| 1/2" | 15mm | ~21.2–21.5 mm |
| 3/4" | 20mm | ~26.6–26.9 mm |
| 1" | 25 mm | ~33.4–33.7 mm |
| 1.5" | 40 mm | ~48.1–48.4 mm |
| 2" | 50 mm | ~60.2–60.8 mm |
| 2.5" | 65 mm | ~75.2–75.5 mm |
To reiterate, these are nominal sizes and are designed to fit matching fittings — not to measure what their name suggests. These are based on PVC Pressure Pipe AS/NZ 1477 Dimensions1.
- º Internal diameters vary slightly by manufacturer and class.
- 1 Not all pool/spa fittings match these dimensions exactly. Some do not follow Australian or international standards. Chinese spas may use proprietary fittings.
Understanding Plumbing Sizes & Nominal Measurements
Plumbing sizes can be confusing. PVC and many other pipe systems use nominal sizes—the size is a name, not the exact measured dimension. This convention is used across most pool and spa systems and other plumbing areas so that pipes and fittings remain compatible.
Why pipe sizes don’t match the measurements
The Nominal Pipe Size (NPS) system standardises pipe dimensions so that pipes, fittings, valves, and accessories interoperate.
Plumbers work with these nominal names every day, but DIYers can be tripped up if they try to match by a tape-measure alone.
How to Measure Pipe Correctly
-
Pipe size is identified by:
- The pipe’s Outside Diameter (OD).
- The fitting’s Inside Diameter (ID) (socket opening).
- Pipe Class / Schedule (e.g., Class 9, 12, 18 or Sch 40) relates to wall thickness and therefore the Internal Diameter (ID) and pressure rating.
- The outside diameter of a fitting is not useful (wall thickness varies by manufacturer).
Hose & Tube Dimensions
Common flexible hose sizes used in pool/spa systems (approximate IDs).
| Imperial Name | Metric Name | Inside Diameter (ID) |
|---|---|---|
| 3/8" | 9–10 mm | ~9 mm |
| 3/4" | 19 mm | ~19 mm |
BSP – British Standard Pipe Thread Sizes
BSP thread names are also nominal. The thread OD will not equal the nominal name.
| BSP Thread Size Naming | Outside Diameter (mm / inch) | TPI |
|---|---|---|
| 1/16" BSP | 7.7 mm / 0.304" | 28 |
| 1/8" BSP | 9.7 mm / 0.383" | 28 |
| 1/4" BSP | 13.16 mm / 0.518" | 19 |
| 3/8" BSP | 16.66 mm / 0.656" | 19 |
| 1/2" BSP / 15 mm | 20.99 mm / 0.825" | 14 |
| 5/8" BSP | 22.99 mm / 0.902" | 14 |
| 3/4" BSP / 20 mm | 26.44 mm / 1.041" | 14 |
| 7/8" BSP | 30.20 mm / 1.189" | 14 |
| 1" BSP / 25 mm | 33.25 mm / 1.309" | 11 |
| 1-1/4" BSP | 41.91 mm / 1.650" | 11 |
| 1-1/2" BSP / 40 mm | 47.80 mm / 1.882" | 11 |
| 2" BSP / 50 mm | 59.61 mm / 2.347" | 11 |
| 2-1/4" BSP | 65.71 mm / 2.587" | 11 |
| 2-1/2" BSP | 75.18 mm / 2.960" | 11 |
| 3" BSP | 87.88 mm / 3.460" | 11 |
| 4" BSP | 113.03 mm / 4.450" | 11 |
| 5" BSP | 138.43 mm / 5.450" | 11 |
| 6" BSP | 163.83 mm / 6.450" | 11 |
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7201750057
