Coming Soon - BWT ES Fibreglass Media Filter - 21in to 36in - Sand and Glass Media

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Model

BWT ES21 - 21in - 40mm Clamp MPV BWT ES25/40 - 25in - 40mm Clamp MPV BWT ES25/50 - 25in - 50mm Bolt On MPV BWT ES28 - 28in - 50mm Bolt On MPV BWT ES32 - 32in - 50mm Bolt On MPV BWT ES36 - 36in - 50mm Bolt On MPV

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BWT ES Fibreglass Media Filter

Top-mounted, 100 percent factory tested, dual-layer fibreglass tank with a 6-way multiport valve and a 10 year tank warranty.

Physically Stocked, unlike most 'drop-shipping' websites.
Shipped from VIC, NSW, QLD, WA

The BWT ES Series is a conventional top-mounted media filter built properly. The tank is wound in dual-layer fibreglass with a UV-resistant reinforced outer surface, so it holds up to full sun on an exposed equipment pad rather than chalking and going brittle after a few summers.

Every unit is factory tested before it ships and comes fitted with a 6-way multiport valve on an angle-adjustable union - a genuinely useful detail on a changeover, where it lets you line the valve up to existing pipework instead of forcing the plumbing to meet the tank. An in-line backwash sight glass, oil-filled stainless pressure gauge and metric/imperial quick connect round out the fittings.

Six tank sizes are available from 21 inch through to 36 inch. The two smaller sizes use a 40mm clamp-style multiport valve, while the 25 inch and larger tanks are available with a 50mm bolt-down multiport valve for higher flow installations.

Key Features

100 percent factory tested
6-way multiport valve with angle-adjustable union to reduce pipe stress
Dual-layer fibreglass tank with UV-resistant reinforced outer surface
In-line backwash sight glass
Oil-filled stainless pressure gauge
Metric / imperial quick connect
L style bayonet laterals
40mm clamp multiport valve on 21in and 25in models
50mm bolt down multiport valve on 25in, 28in, 32in and 36in models
Runs on sand or glass media

Models and Dimensions

Model	Valve	Height (mm)	Diameter (mm)	Sand (kg)	Glass Fine (kg)	Glass Coarse (kg)	Flow (LPM)
BWTES21	40mm Clamp	680	500	100	30	45	185
BWTES25/40	40mm Clamp	740	650	150	75	45	260
BWTES25/50	50mm Bolt On	800	650	150	75	45	270
BWTES28	50mm Bolt On	840	700	225	120	60	340
BWTES32	50mm Bolt On	960	800	325	225	90	355
BWTES36	50mm Bolt On	1025	900	450	255	120	520

Operating Limits

Maximum water temperature: 43 degrees C
Maximum working pressure: 2.5 bar
Mounting: top-mounted multiport valve

Sand or Glass Media

These tanks will run on either graded filter sand or crushed glass media. Glass media filters finer, weighs less per tank fill, resists channelling and typically lasts longer between changeouts, though it costs more up front. The media quantities for both options are listed in the table above - note that a glass fill uses a coarse bottom layer and a fine top layer.

Warranty

10 years - filter tank
12 months - multiport valve

Sizing Guidance

Match the filter to the pump, not the other way around. A filter that is too small for the pump pushes water through the media too fast, which drops filtration quality and drives up pressure. As a general rule, choose a tank whose maximum flow rate comfortably exceeds your pump output at operating head. Oversizing the tank slightly is never a problem and extends the interval between backwashes.

Note: This product must be installed and serviced by a qualified pool equipment technician or licensed professional. We carry more spare parts than anyone.

Manufacturer Brochures, Manuals & Part Numbers

Need specifications, lateral and internals part numbers, dimensions or more product information? See the manufacturer documents:ES Series Brochure | Instruction Manual - 40mm Clamp Models | Instruction Manual - 50mm Bolt On Models

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 Dimensions^1.

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.

Quick example: A 2" / 50 mm fitting is named for the pipe it connects to, but the pipe’s actual outside diameter (OD) is approx. 60.3 mm (typically ~60.2–60.5 mm in AS/NZ pressure pipe).

Another example: a 2” / 50mm o-ring may refer to a barrel union, etc that suits 50mm pipe. Eg: a “50mm Balboa Gasket” refers to a heater gasket that measure 74mm across, but suits a Balboa barrel union made for 50mm pipe (and the 50mm pipe does not measure 50mm either!)

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).

Important: For pool/spa work, most plumbing uses Pressure Pipe (AS/NZ standards) — not DWV. Always check OD and the pipe class against your equipment specifications.

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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BWTES21

Important Information

Delivery Pricing & Options

*Free Road Shipping on orders over $149.00 Australia-wide
Capped Road Freight Shipping at $19.95
Express Post available on many products. Contact us before ordering if urgent.
Shipping to Australia & New Zealand Only
Shipping Policy & Info
About Us

Heater & Spa Parts is built on decades of real pool and spa industry experience, from manufacturer R&D and consulting to in-field spa repairs, pool heater servicing, trade support and diagnostics.
We understand how the equipment works, why it fails, and why it should be replaced.
More Parts than Anyone

We are a real Australian store with real stock, not a drop shipper.
With 100,000+ parts across 10,000+ product lines, we stock spa parts, pool heater parts, filters, pumps, jets, chemicals, touchpads, control panels, manuals and more, backed by fast dispatch and practical advice.
Pick-Ups

Pickup for many items is available from our Carrum Downs, VIC store at 10 Industry Blvd, Carrum Downs.
If pick-up is urgent, contact us before ordering.
Our NSW, QLD and WA warehouses currently ship orders only, with no retail counter available yet.

Brand Information

We are an authorised dealer, retailer, and/or service & warranty agent for many leading brands, including: Fluidra (AstralPool, Zodiac, Hurlcon), Aeware, Air Supply of the Future, Aqua-Flo, Balboa, Celsior, CG Air, CMP, Custom Moulded Products (CMP), Darlly, Davey, Del Ozone, Dontek, Edgetec, Emaux, Filtrite, Gecko, Goulds, Harwil, Henden, Herga, Honeywell, HydroAir, HydroQuip, ITT, Jandy, Joyonway, Laing, Len Gordon, Lo-Chlor, LX, LX Whirlpool, Magic Plastics, Magnum, Monarch, Onga, Pentair, PoolSystems, Presair, Raypak, Reemay, Rheem, Rising Dragon, S&P, Sensaheat, Spa-Craft, Spa-King, SpaNet, Spa-Quip, SpaTex, SpaZazz, Tecmark, Therm Products, Thermcore, Waterco, Waterway, Weld-On, Whirlpool, Xylem, and others.

We also sell parts for many spa and swim spa brands, including parts to suit Alpine Spas, Artesian Spas, AquaPulse Spas, Balboa spas, Bullfrog Spas, Caldera Spas, Canadian Spa Company, Cedar Spas, Chinese import spas, Coast Spas, Costco spas, Cyclone Spas, Davey spas, Decina, Designer Spas, Dimension One Spas, eBay spas, Endless® Spas, Fastlane Pools, Fisher Spas, Gecko spas, Halo Spas, H2O Spas, H20 Spas, Heritage Spas, HotSpring Spas, HydroQuip spas, Impact Spas, Jacuzzi, Just Spas, Just Swim Spas, LA Spas, Lanark Spas, Leisurite Spas, Maax Spas, Monarch Spas, MySpa, O2 Spas, Oasis, Sapphire Spas, Sapphire Swim Spas, SCS Spas, Signature Spas, Silver Spas, Spa Industries, Spa-Quip spas, SpaNet spas, Spas Direct, Sundance Spas, Sunrans, SwimEx, Trueform Spas, Tuff Spas, Urban Pool, Vortex®, Vortex® Swim Spas, and many others.

Handy PVC Plumbing Size Info
Plumbing sizes can be confusing. Pressure PVC pipe use nominal sizes - the size is simple a name, not the measured dimension. This convention is used across most pool and spa systems so that pipes and fittings remain compatible.
- 50mm / 2" = ~60-61mm OD
- 40mm / 1.5" = ~48mm OD
- 25mm / 1" = ~33-34mm OD

Plug Types & Styles
Common plug types found on spa equipment are AMP, Mini JJ, C38 (Aus 3-pin), Gecko in.link, etc.
To view plug types, click here.
- AMP plugs are the most common type used for over 20 years.
- Almost all Mini J&J plugs are no longer available and must be modified.
- C38 is the common Australian 3-pin plug found in normal household outlets.
- Gecko (Aeware) in.link style plugs are no longer available and must be modified.

General Information & Disclaimers

Many products we supply are OEM-supplied and may not include retail packaging, printed instructions, or accessories. Refer to the product listing for details, or contact us if unsure.

Product images are for illustration only. Actual items may vary due to manufacturer changes, updates, and other variations. Images may show a full assembly, a partial assembly, or a specific component only. They are provided for identification purposes and do not by themselves define what is included. Please read the title and description carefully.

All products must be installed and used by qualified and experienced persons in accordance with applicable Australian standards and manufacturer requirements. We are a parts supplier, similar to an electrical, plumbing, or automotive parts supplier. We sell parts, but cannot always provide exact installation, troubleshooting, or system design advice. Buyers are expected to know what they are doing or use a qualified professional.

® Trademark Information

All trademarks, brand names, and logos displayed on this website are the property of their respective owners. Heater & Spa Parts is an independent Australian supplier of replacement parts and accessories. Use of trademarked names, logos, and brands is for identification and compatibility purposes only, unless otherwise stated.