Unicel 4CH-35 Replacement Filter Cartridge | 35 Sq. Ft. | Sundance & Hot Springs Spas

Keep your spa running clean with the Unicel 4CH-35 from the 4000 Series — a 35 square foot replacement filter cartridge engineered for spa filter housings that use a 1-1/2" male threaded bottom connection. With 145 pleats of 3 oz. Reemay 2033 polyester media, the 4CH-35 delivers reliable debris capture and extended service life in a compact 16" form factor.

⚠️ IMPORTANT: Verify Your Bottom Fitting Before Ordering
The 4CH-35 has a 1-1/2" male pipe thread (MPT) on the bottom cap — it requires a threaded connection in your filter housing. If your current filter uses a 1.9" inside diameter slip-fit receptacle, a disposable adapter is required (adapter not included). Verify your existing filter's bottom fitting type before ordering.

Specifications

Filter Area	35 sq. ft.
Length	16"
Outer Diameter	4 5/8"
Top Inner Diameter	N/A
Bottom Inner Diameter	N/A
Material	3 oz. Reemay 2033
Pleat Count	145
Top Cap: molded cone handle	Bottom Cap: 1-1/2" male thread/MPT

Fits into:

(This is not an exhaustive list.)

Pro Tip: Before ordering, confirm your existing cartridge measures 16" long with a 4 5/8" outer diameter and a male-threaded bottom. The 145-pleat Reemay 2033 media provides an optimal balance of filtration surface area and flow rate for residential spa applications.