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Hydro Spas Filters

Hydro Spas hot tubs use one of three filters. Pull your filter, measure it and match it to the cards below — every brand and pack size is on its page.

Your Hydro Spas filter, by cartridge

Not sure? Measure the diameter across the end cap, the length end to end, and check the top and bottom — open, handle, threaded or slip fit. Or send a photo of your filter through the form below and we will confirm the fit.

Shop: All Hot Tub Filters | Ego3 Reusable Filters

Resources: Compare Filter Brands | Water Care

Showing all 5 resultsSorted by price: high to low

✅ Not Sure It Fits? Verify Before Ordering

Hot tub filter fitment varies by spa brand, model, year, filter size, thread style and top/bottom style.

To confirm the correct replacement, send clear photos of:

  • The label or end cap of your current filter
  • Your spa serial number sticker
  • The filter well with the filter removed (so we can see the fitting)

EZ Hot Tub Parts confirms fitment before you order, so you do not pay return freight on a wrong filter.

Hydro Spas filter buying guide

47 sq ft outside thread — 6CH-47. 6″ across, 9-1/8″ long, handle top, male pipe thread (MPT) bottom. Fits select Hydro Spas models that use the 47 sq ft outside thread cartridge. Options: ProAqua, Darlly. Singles, 2 packs and 4 packs are available.

25 sq ft outside thread — 4CH-24. 4-5/8″ across, 9-3/4″ long, injection molded cone handle top, male pipe thread (MPT) bottom. Fits select Hydro Spas models that use the 25 sq ft outside thread cartridge. Options: ProAqua, Darlly. Singles, 2 packs and 4 packs are available.

35 sq ft drop-in style — C-4401. 4-15/16″ across, 4-5/8″ long, open top, open bottom. Fits select Hydro Spas models that use the 35 sq ft drop-in style cartridge. Options: ProAqua. Singles, 2 packs and 4 packs are available.

Use the buttons on each filter page to switch brand or pack size.

Not sure which filter brand is right for you? Compare Hurricane, OEM Factory Direct, Pleatco, ProAqua, Darlly and Ego3.

Keep your filters working longer: High Pressure Filter Nozzle | Filter Cleaner | Water Care — and every order over $99 ships free, so a spare set plus cleaner usually rides along at no extra cost.

Hydro Spas filters: 47 sq ft Outside Thread (ProAqua) | 25 sq ft Outside Thread (ProAqua) | 35 sq ft Drop-In Style (ProAqua)

Hydro Spas filter questions

What filter does my Hydro Spas hot tub use?

Depending on the model, Hydro Spas hot tubs use the 47 sq ft outside thread (6CH-47), the 25 sq ft outside thread (4CH-24) or the 35 sq ft drop-in style (C-4401). Measure your old filter and match the size and the bottom style, or send us a photo.

How do I tell which filter I have?

Measure the diameter across the end cap and the length end to end, then look at the bottom: open, threaded (outside or inside) or slip fit. The filter specs on each product page list all four.

Is the PTL47W-P the same as the 6CH-47?

Yes. Pleatco PTL47W-P and Unicel 6CH-47 are the same 47 sq ft cartridge from two different makers; the cross-reference list on each product page shows the other equivalent numbers.

Is the PGS25P4 the same as the 4CH-24?

Yes. Pleatco PGS25P4 and Unicel 4CH-24 are the same 25 sq ft cartridge from two different makers; the cross-reference list on each product page shows the other equivalent numbers.

Is the PRB17.5SF-PAIR the same as the C-4401?

Yes. Pleatco PRB17.5SF-PAIR and Unicel C-4401 are the same 35 sq ft cartridge from two different makers; the cross-reference list on each product page shows the other equivalent numbers.

How often should I replace my Hydro Spas filter?

Every 12 months, with a rinse every 2–4 weeks and a monthly soak in filter cleaner. Keeping a second filter to rotate makes both last longer.

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