Coming Soon - BWT Diamond pH & ORP Sensors and Sensor Housing - Diamond Mineraliser / Diamond Dose
Coming Soon - BWT Diamond pH & ORP Sensors and Sensor Housing - Diamond Mineraliser / Diamond Dose - 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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Coming Soon - BWT Diamond pH & ORP Sensors and Sensor Housing - Diamond Mineraliser / Diamond Dose - is temporarily out of stock and will ship as soon as it's available.
BWT Diamond pH & ORP Sensors and Sensor Housing
Replacement and add-on probes for the BWT Diamond Dose and Diamond Mineraliser.
- Physically Stocked, unlike most "drop-shipping" websites.
- Shipped from VIC, NSW, QLD, WA
pH and ORP probes are consumable items. They drift with age, chemical exposure and cleaning, and need replacing when they can no longer be calibrated or remain unstable after proper circulation and stabilisation.
A BWT Diamond Mineraliser and Diamond Dose are required. These sensors do not operate standalone.
pH Sensor
Continuously monitors pH so automatic acid dosing can be managed safely, accurately and regularly. Enables Auto (pH Probe) mode on the Mineraliser, dosing acid only when measured pH rises above the target setpoint. Recommended target range is pH 7.2 - 7.6, depending on pool surface.
ORP Sensor
Monitors the water's oxidation-reduction potential in millivolts and signals the Mineraliser to adjust chlorine output to suit the pool's actual demand. Enables Auto (ORP Probe) mode. ORP indicates oxidising potential rather than a free chlorine figure in ppm, and is affected by pH, stabiliser, salt level, water temperature and bather load.
Sensor Housing
The sensor manifold that holds the pH and ORP probes in the circulation line, keeping the probe tips wet and correctly positioned for stable readings.
Probe Care
- Keep probe tips wet at all times
- Store removed probes in the manufacturer's recommended storage solution - never dry, and never in distilled or demineralised water
- Do not clean with abrasive materials, brushes, metal tools or strong chemicals
- Allow 24 - 72 hours of normal circulation for a new, cleaned or chemically exposed probe to stabilise before fine setpoint adjustment
- Check probe readings regularly against a pool water test, and calibrate the pH probe when required
- Replace a probe if it cannot be calibrated, remains unstable, or is physically damaged
Reading Accuracy
ORP sensors vary from unit to unit - two probes in the same water can differ by several tens of millivolts, particularly straight after installation or cleaning. Correct pH before relying on an ORP reading: high pH reduces chlorine effectiveness and makes ORP read low even when a test kit shows adequate free chlorine. High stabiliser and high salt levels also lower measured ORP.
Note: Regular manual water testing is still required, even with pH and ORP automation installed. We carry more spare parts than anyone.
Manufacturer Brochures, Manuals & Part Numbers
Need specifications, part numbers, wiring diagrams or more product information? See the manufacturer documents: Diamond Mineraliser Brochure | Full User Manual
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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