Unicel Replacement Filter Cartridge 50 sf | 4CH-50
Unicel
SKU: 4CH-50
Unicel 4CH-50 Replacement Spa Filter Cartridge – 50 Sq Ft (4" OD x 14" Length, 1-1/2" MPT Threaded Bottom)
The Unicel 4CH-50 is a high-capacity 50 sq ft pleated spa filter cartridge designed for select hot tubs and spa filter canisters that use a threaded screw-in bottom connection. With its compact 4" diameter body and taller pleat pack, it provides strong debris capture and longer run time between cleanings compared to smaller cartridges.
Key Features
- 50 sq ft filtration area for clearer water and steady circulation
- Bottom: 1-1/2" male pipe thread (MPT) screw-in connection
- Top: open end for compatible standpipe/canister designs
- Durable pleated media and rigid core built for repeated cleaning cycles
- Ideal replacement when pleats are torn, flattened, or the cartridge stays restrictive after cleaning
Specifications
- Part Number: 4CH-50
- Filtration Area: 50 sq ft
- Outside Diameter: 4"
- Length: 14"
- Top End Cap: Open
- Top Inside Diameter: 2" (open)
- Bottom End Cap: 1-1/2" MPT thread
- Pleat Count: 220
- Media: 3 oz pleated media
Replaces / Cross References
- Pleatco: PWW50P3
- Filbur: FC-0172
- Darlly: 40505
- Baleen: AK-4003
- Other common references: 40025, 210-0100, 8CH-950 (verify by dimensions and thread style)
Compatibility Notes
- This cartridge uses a threaded bottom (1-1/2" MPT). If your current filter has a different thread size (or a slip/non-threaded bottom), you need a different cartridge.
- Always confirm fit by matching the 4" OD, 14" length, and 1-1/2" threaded bottom.
When to Replace
- Flow is weak or the spa struggles to maintain circulation even after cleaning
- Pleats are torn, frayed, flattened, or separating from the end caps
- The cartridge quickly plugs up again after rinsing
- End caps or the threaded connection are cracked/warped and won’t seal properly
Related Products
- Unicel 4CH-50 (Shop / Options)
- Spa Cartridge Filter Cleaner
- Cartridge Cleaning Wand
- Spa Water Test Strips
- Spa Fill / Hose Pre-Filters
- Silicone O-Ring Lubricant (Pool/Spa)
Maintenance Tips
- Rinse the cartridge regularly (often weekly with heavy use) to prevent restriction and keep flow strong.
- Deep clean every 3–6 weeks with a cartridge cleaner to remove oils; rinse thoroughly before reinstalling.
- If scale is present, degrease first, then treat for scale (never reverse the order), and rinse completely.
- Rotating between two cartridges (one in use, one drying after cleaning) can extend overall filter life and improve filtration performance.
Questions about returns? View our return policy.
Hours Of Operation:
Monday - Friday: 7:00 am to 5:00 pm Phoenix Time
Saturday: 8:00 am to 2:00 pm
Sunday: Closed
- We do not ship on Saturday or Sunday.
- Orders totaling more than $300 will require signature confirmation upon delivery.
- We process and prepare orders for shipment within 1 business day. Please note that many other pool supply retailers require 3–5 days of handling time before shipping.
- Orders placed after 1:00 pm Phoenix Time may not be eligible for same-day shipment.
- Expedited shipping options are available at checkout.
Return Policy:
- Products that are received damaged will receive a refund in store credit.
- Most products are eligible for return within 30 days of receipt, except where noted below.
- To initiate a return, please complete an RMA form prior to sending your item back.
- Original shipping costs are non-refundable and will be deducted from the return credit.
- Items returned missing accessories or original packaging, or that are not in the same condition as received, may be subject to a restocking fee of up to 100% depending on the condition of the item upon return.
- Some returns will be charged an automatic 15% restocking fee.
- We are unable to issue refunds for items that have been damaged or rendered inoperable due to installer error.
- Please complete the return form to receive your RMA number and return shipping label.
- Chemical products are not eligible for return under any circumstances.
- The Pentair Colorsync 618031 is not eligible for return.
- Pool cleaners are not eligible for return.
- Opened seals and o-rings are not eligible for return.
- Capacitors are not eligible for return.
- Plastic popup tools are not eligible for return.
- Automation components and circuit boards are not eligible for return.
- If a light is returned due to a reported malfunction and is found to be fully operational upon testing, return shipping costs and a restocking fee will be deducted from the refund.
- Orders refused at the time of delivery will be subject to the original shipping costs being deducted from the refund.
Related Products
