Astralpool Cell Nut 70390 - E-Series, VX, Viron, eQuilibrium & Halo - Genuine Chlorinator Spare Part
Astralpool Cell Nut 70390 - E-Series, VX, Viron, eQuilibrium & Halo - Genuine Chlorinator Spare Part 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.
Delivery and Shipping Info*
Delivery and Shipping Info*
Free Shipping over $99 for most products. Choose Express Post for fastest shipping!
Astralpool Cell Nut 70390 - E-Series, VX, Viron, eQuilibrium & ...
Astralpool Cell Nut 70390 - E-Series, VX, Viron, eQuilibrium & Halo - Genuine Chlorinator Spare Part is temporarily out of stock and will ship as soon as it's available.
Astralpool Cell Nut 70390 - E-Series, VX, Viron, eQuilibrium & Halo
Genuine Astralpool 70390 - the cell nut, the threaded locking ring that clamps the electrode into the external clear cell housing and holds the seal. Part 5 in the manufacturer's parts diagram.
- We keep these physically in stock for fast shipping or local pick-up, unlike most drop-shipping websites.
- Shipped from VIC, NSW, WA, QLD
Suits the following chlorinators
- Astralpool E-Series - E25, E35
- Astralpool / Hurlcon VX Series - VX6, VX7, VX9, VX11 and T variants
- Astralpool Viron - V18, V25, V35, V45
- Astralpool Viron eQuilibrium - EQ18, EQ25, EQ35, EQ45
- Astralpool Halo - Halo 18, Halo 25, Halo 35, Halo 45
- Filtrite branded chlorinators using the same cell housing
The cell housing hardware is common across these ranges. The electrodes are not - VX and E-Series use the 219xx cell range, while Viron, eQuilibrium and Halo use the 129xx range.
Cell nut or cell nut cup? They are different parts
- 70390 - cell nut: this product. The threaded ring that locks the electrode into the housing.
- 70391 - cell nut cup / terminal cover: the cup that sits over the top and shields the cable connection from weather. Buy the nut cup here.
When to replace it
- Nut is cracked or split, commonly from over-tightening
- Threads are stripped or crossed and will not pull the cell down evenly
- Cell weeps at the housing because the nut no longer clamps square
- Nut has gone brittle with age and UV exposure
These are hand-tight only. Fitting a new nut with a wrench is the most common way the replacement fails as quickly as the original. If the cell still weeps with a sound nut, the o-ring is the more likely cause.
Related Parts
- 78104 - cell body o-ring. Replace whenever the cell is opened (buy here)
- 70391 - cell nut cup / terminal cover (buy here)
- 70570 - external clear cell body, the V4 housing (buy here)
See the full range of genuine Astralpool and Zodiac chlorinator cells and electrodes.
Before ordering
Chlorinator cell hardware changed across production periods, and older VX housings use different components to the current V4 housing. Confirm this part is correct for your equipment before ordering. Use the catalogue below, seek professional assistance, or contact us 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.
Manufacturer Catalogues, Diagrams & Part Numbers
Need exploded views, spare part numbers, product numbers, diagrams, or more product information? See the manufacturer catalogues: Astralpool Catalogue 2026 | Zodiac Catalogue 2026
Common search terms: Astralpool 70390, Astral 70390, chlorinator cell nut, cell locking nut, cell retaining ring, VX cell nut, Viron cell nut, EQ cell nut, Halo cell nut, E-Series cell nut, Hurlcon cell nut, WWDG SpaPro.
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 |
Payment & Security
We accept: Visa, Mastercard, Amex, Apple Pay, Google Pay, ShopPay, Paypal, Zip, Afterpay
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
70390
