Astralpool / Zodiac Body Only ZX 310 Filter 7821702

Astralpool ZX 310 Cartridge Filter Tank Body — 7821702 (also Zodiac ZXC 310, Filtrite CF, Aquatight)

This is the genuine Astralpool tank body for the twin-element ZX 310 cartridge filter, part number 7821702. It is the lower pressure vessel that holds the cartridge elements — supplied on its own, to replace a tank that has cracked, split, crazed or is leaking below the lid. The ZX 310 is the tallest filter in the range: it runs two elements joined end-to-end by a coupler.

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

This is the same filter sold under several brands — Astralpool ZX, Hurlcon ZX, Zodiac ZXC, Filtrite CF and Aquatight. The Zodiac ZXC is simply the Zodiac-badged Astralpool ZX. Tank colour and part number have both changed across production runs, so confirm the model before ordering.

The ZX Body Match Rule (rev. ZXB-1.0)

A tank body is sized to the filter model, not to the plumbing, so match it by model badge and confirm with the element count:

1. Find the model number on the filter label, or moulded into the lid or tank. It reads ZX310 (or the Zodiac ZXC310).
2. This body, part 7821702, is the correct tank for the ZX 310 / ZXC 310 only.
3. Confirm physically: open the filter. The ZX 310 is a twin-element tank — inside you will find two cartridge elements (78088) joined end-to-end by an element coupler (78078). The single-element ZX filters (50 to 250) do not have a coupler.
4. If your badge reads ZX310 and you have two elements with a coupler, this is your body. A single-element ZX needs a different, shorter tank — see the chooser below. Note: Astralpool XC is a separate, unrelated series and does not use this tank.

Worked Example

A customer at Gisborne has a tall filter with an unreadable label. They open it and find two stacked cartridge elements joined by a plastic coupler in the middle, and the tank shoulder is moulded ZX310. Twin element + coupler + ZX310 badge — so this 7821702 body is correct. They order the body with a new tank O-ring (78110), a fresh pair of 78088 elements and a new 78078 coupler, since the old coupler is usually as tired as the tank.

Which Tank Body Do I Need?

Will Not Fit — Order The Correct Tank Instead

• ZX50 / ZX75 (ZXC50/75) — short single-element tank. Use the ZX50/75 body (7821102).
• ZX100 / ZX150 (ZXC100/150) — single-element tank. Use the ZX100/150 body (7821202).
• ZX200 / ZX250 (ZXC200/250) — single-element tall tank. Use the ZX200/250 body (7821302).
• Astralpool XC — a separate, unrelated filter series. The XC tank is not interchangeable with the ZX / ZXC tank despite the similar name. Contact us with your model and a photo.
• Hurlcon QX — a different filter with a 222mm lid, not part of the ZX family.

Compatible Filters — ZX 310 Twin-Element

This 7821702 tank body serves the 310 in each of these — all the same filter under different badges:

• Astralpool ZX / Hurlcon ZX: ZX310
• Zodiac ZXC: ZXC310
• Filtrite CF / Aquatight: ZX310-equivalent twin-element cartridge filters built on the ZX 310 tank

Matching cartridge elements: ZX310 elements — 78088, supplied as a pair · joined with the element coupler — 78078.

What's Included

• ZX / ZXC 310 filter tank body (lower pressure vessel), part 7821702

Not included: lid assembly, tank O-ring, cartridge elements, element coupler, pressure gauge and plumbing unions are separate items. Fit a new tank O-ring whenever you replace a tank — the old seal has taken a set to the old tank's sealing face.

Measurements & Identification

• Fits model: ZX310 / ZXC310 (twin-element)
• Elements: two 78088 elements joined by the 78078 coupler
• Part number: 7821702 (supplied as SP7821702)

Symptoms Of A Failed Tank

• A crack, split or weep low on the tank body, below the lid seal
• Water tracking down the outside of the tank when the pump runs
• Crazing or brittleness in the moulding from years of UV exposure
• A tank that has been over-pressurised, distorted or impact-damaged

Fitting Notes & Safety

• These are pressure vessels. Never work on the filter with the pump running or the system pressurised. Shut down, isolate power, close valves and release all pressure at the air bleed before you start.
• Transfer your fittings — drain cap, union tails and any bulkhead fittings — to the new tank, renewing their O-rings.
• Fit a fresh tank O-ring and lubricate it with a silicone-based lubricant only. Petroleum grease swells and destroys the seal.
• Check the element coupler when the tank is apart — a split coupler lets unfiltered water bypass both elements.
• Hand-tighten the locking ring only. Over-tightening is what cracks lids and rings — and a fresh tank deserves a fresh start.
• On recommissioning, open the air bleed until water flows steadily, close it, and note the clean starting pressure on the gauge. Clean the elements when pressure climbs 15–20 kPa above that figure.

Related ZX / ZXC Filter Parts

• ZX310 element coupler — 78078
• ZX / ZXC lid assembly with handles & locking ring — SP7820502
• ZX / ZXC tank O-ring (lid seal) — 78110 / 78105
• ZX / ZXC air bleed plug & O-ring
• Full Astralpool ZX / Zodiac ZXC cartridge filter range & spare parts

Part Numbers & Search References

This tank body: 7821702 · SP7821702 · Body Only ZX310 · Astralpool ZX310 tank · Zodiac ZXC310 filter body · Hurlcon ZX310 filter body · twin-element ZX filter housing · Filtrite CF310 body · Aquatight ZX310 tank · Astral pool filter tank replacement.

Frequently Asked Questions

Is this the tank for the twin-element ZX310?
Yes. Part 7821702 is the ZX310 tank body. The ZX310 runs two 78088 elements joined by the 78078 coupler inside this one tank.

How do I know I have a ZX310 and not a smaller ZX?
Read the model number on the filter label or moulded into the tank, and open the filter. The ZX310 reads ZX310 or ZXC310 and has two elements joined by a coupler. A single element with no coupler means a smaller ZX and a different tank.

My filter is a Zodiac ZXC. Is this the right body?
Yes. The Zodiac ZXC is the same filter as the Astralpool ZX, just Zodiac-badged. If it reads ZXC310, this 7821702 body is correct.

My filter is an Astralpool XC. Is this the right body?
No. The XC is a separate, unrelated filter series and does not share the ZX / ZXC tank body. Contact us with your model and a photo and we will match the correct part.

Does the body come with the lid, O-ring, elements or coupler?
No. The tank body is supplied on its own. The lid assembly, tank O-ring, cartridge elements and coupler are separate items, all linked on this page. Fit a new O-ring whenever you replace a tank.

The ZX range is discontinued. Can I still get this body?
Yes. The ZX filter range has been superseded, but the serviceable parts including this tank body are still available. Replacing a tank on an otherwise sound filter is far cheaper than a whole new unit.

Is this a genuine Astralpool part?
Yes. This is the genuine Astralpool tank body, part 7821702. It is a special-order item.

Why would I replace the tank body rather than the whole filter?
A cracked or leaking tank is usually the only failed component. If your lid, ring, gauge and plumbing are sound, replacing just the body restores the filter at a fraction of the cost of a new one.

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

As with all products, these must be diagnosed and fitted by a qualified and experienced person. This is a special-order item.