2 Pack of replacement Vita Spas filters (19 sq ft outside thread) — ProAqua High Flow
Fits select Vita Spas models that use the 19 sq ft outside thread cartridge. Vita Spas used more than one filter size over the years, so match the diameter, length, and top and bottom style below to the filter you are replacing — or send us a photo and we will confirm before you order.
ProAqua high-flow filters were formerly sold under the Proline name — same filter, same high-flow core, new name.
Not sure which filter brand is right for you? Compare hot tub filter brands here.
Did you know the number one reason for hot tub freeze damage is a dirty filter? Dirty filters also cause additional stress on the pump/motor and leads to premature failure.
Proper Filter Care System:
- Have 2 sets of filters
- Install clean filter
- Rinse dirty filter with high pressure nozzle
- Verify no debris left between pleats, before storing on shelf to dry
- Once a month soak filters in a filter cleaner solution
Filter Specs:
- Diameter – 4-5/8″
- Length – 8″
- Top: Injection Molded Cone Handle
- Bottom: Male Pipe Thread (MPT)
- SQFT: 19
What’s in the box: two filter cartridges.
✅ Not Sure It Fits? Verify Before Ordering
Hot tub part compatibility can vary by spa brand, model, year, serial number, control system, and part revision.
To help us identify the correct replacement part, please send clear photos of:
- Your existing part label or sticker
- Your spa serial number sticker
- The equipment area or installation location (if accessible)
EZ Hot Tub Parts can help confirm fitment before you order and help reduce costly returns.
It fits the Vita Spas models that use a 19 sq ft outside thread cartridge measuring 4-5/8″ in diameter and 8″ long. Measure your old filter end to end and across the end cap — if the numbers match, it fits. Still unsure? Use the fitment form above and send a photo of your filter.
Measure the diameter across the end cap and the total length from end to end, then check the top (open, closed, handle) and the bottom (open, threaded, slip fit). This cartridge is 4-5/8″ x 8″, top: injection molded cone handle, bottom: male pipe thread (mpt).
This cartridge cross-references to: Unicel 4CH21, Pleatco PTL18P-4, Filbur FC-0121, 17-175-1025, 11901, PTL18P, 20245238, PVT25N, PTL18, PTL18W/PADAD, R173372, XLS-437, ProLine P4CH-21.
Yes. ProAqua is the new name for the Proline high-flow line — same filter, same high-flow core.
Rinse it every 2–4 weeks, deep-clean it monthly with filter cleaner, and replace it every 12–24 months or sooner if the pleats are torn, flattened, or the end caps are cracked. Keeping two sets and rotating them makes each set last longer.
A second set means you always have a clean, dry filter ready to drop in while the other set soaks. Multi-packs also cost less per filter than buying singles.
PA-421 Unicel 4CH21 Pleatco PTL18P-4 Filbur FC-0121 17-175-1025 11901 PTL18P 20245238 PVT25N PTL18 PTL18W/PADAD R173372 XLS-437 ProLine P4CH-21
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