4 Pack of replacement Cal Spas filters (50 sq ft outside thread) — Darlly
Fits select Cal Spas models that use the 50 sq ft outside thread cartridge. Cal 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.
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 – 5-3/16″
- Length – 12-1/2″
- Top: Handle
- Bottom: Male Pipe Thread (MPT)
- SQFT: 50
What’s in the box: four 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.
Helpful photos: serial number sticker, equipment labels, full equipment view, and any damaged or leaking parts.
It fits the Cal Spas models that use a 50 sq ft outside thread cartridge measuring 5-3/16″ in diameter and 12-1/2″ 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 5-3/16″ x 12-1/2″, top: handle, bottom: male pipe thread (mpt).
This cartridge cross-references to: Darlly 50501, Pleatco PPM50SC-F2M, Filbur FC-0195, Unicel 5CH-502, 17-175-1513, 15049, 303279, 37-0237, 370-0237, C-5303, FC-0196, FC-1095, FIL11100204, PCAL42-F2M, PPM50-SC, XLS-522, XLS-525, 13507, 20041.
This is a Darlly replacement cartridge. Compare it with the other filter brands we carry on our filter brand comparison page.
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.
17-777-1513 PA-5502 Darlly 50501 Pleatco PPM50SC-F2M Filbur FC-0195 Unicel 5CH-502 17-175-1513 15049 303279 37-0237 370-0237 C-5303 FC-0196 FC-1095 FIL11100204 PCAL42-F2M PPM50-SC XLS-522 XLS-525 13507 20041
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