Pentair Sta-Rite System:3 S7M400 Inner Filter Cartridge, 136 Sq Ft 25021-0223S
Pentair
SKU: 25021-0223S
Pentair Sta-Rite System:3 S7M400 Inner Filter Cartridge, 136 Sq Ft | 25021-0223S
The Pentair 25021-0223S Sta-Rite System:3 Inner Replacement Filter Cartridge is a genuine OEM filtration module designed specifically for the Sta-Rite System:3 S7M400 Modular Media swimming pool filter. Providing 136 square feet of filtration area, this inner cartridge works together with the separately sold 264-square-foot outer cartridge to deliver 400 square feet of total filtration capacity.
Engineered with pleated filtration media and a modular design, this replacement cartridge helps capture dirt, debris, and suspended particles while maintaining efficient water circulation. It is designed to replace the original inner filter element without requiring replacement of the complete filtration system.
Key Features
- Genuine Pentair OEM Replacement: Manufactured for the Sta-Rite System:3 S7M400 filter.
- 136 Sq Ft Filtration Area: Provides the inner portion of the S7M400's 400-square-foot filtration system.
- Modular Media Design: Works with the matching outer cartridge for balanced water flow and effective filtration.
- Durable Pleated Media: Designed to capture dirt and debris while providing effective filtration performance.
- Easy Maintenance: Cartridge can be removed and rinsed according to the manufacturer's cleaning instructions.
- Direct Replacement: Fits the inner cartridge position of the Sta-Rite System:3 S7M400.
- Residential Pool Applications: Designed for compatible inground swimming pool filtration systems.
Product Specifications
- Manufacturer: Pentair
- Brand: Pentair / Sta-Rite
- Manufacturer Part Number: 25021-0223S
- Product Series: System:3 Modular Media
- Product Type: Inner Replacement Filter Cartridge
- Compatible Filter Model: S7M400
- Filtration Area: 136 Square Feet
- Cartridge Position: Inner / Small Module
- Outside Diameter: Approximately 8-5/8 Inches
- Cartridge Length: Approximately 25-3/8 Inches
- Top Opening: 4 Inches, Castle Style
- Bottom Opening: 4 Inches, Castle Style
- Filter Media: Pleated Cartridge Media
- Pool360 Product Number: STA-06-285
- UPC: 022315302266
- Quantity: 1 Inner Filter Cartridge
Compatible Pool Filters
This cartridge is designed specifically for:
- Pentair Sta-Rite System:3 S7M400 Modular Media Filter
- Sta-Rite System:3 400 Sq Ft Cartridge Filter System
Compatibility Note: The 25021-0223S is the inner cartridge for the S7M400 model. Other System:3 models, including the S7M120, S8M150, and S8M500, require different replacement cartridges.
Inner and Outer Cartridge Configuration
The Sta-Rite System:3 S7M400 uses two separate filter cartridges that work together to provide a combined 400 square feet of filtration.
| Cartridge | Part Number | Filtration Area |
|---|---|---|
| Inner Cartridge | 25021-0223S | 136 Sq Ft |
| Outer Cartridge | 25022-0224S | 264 Sq Ft |
| Combined Filtration | Both Cartridges | 400 Sq Ft |
This product includes only the 136-square-foot inner cartridge. The outer cartridge must be purchased separately if replacement of both modules is required.
When Should the Filter Cartridge Be Replaced?
Filter cartridges should be inspected regularly for signs of wear and deterioration. Replacement may be necessary when:
- Filter pressure remains elevated after thorough cleaning.
- Water flow is noticeably reduced despite normal pump operation.
- Filter pleats are torn, flattened, or deteriorated.
- The cartridge end caps or internal support structure are damaged.
- Debris buildup cannot be removed through normal cleaning.
- Filtration performance declines despite proper pool water chemistry.
Installation and Maintenance
- Turn off the pool pump and completely relieve pressure from the filtration system.
- Open the Sta-Rite System:3 filter housing according to Pentair's instructions.
- Remove the existing filter cartridges to access the inner module.
- Remove the old 136-square-foot inner cartridge.
- Inspect and clean the filter housing and internal components.
- Install the new Pentair 25021-0223S inner cartridge in the correct position.
- Reinstall the outer cartridge and reassemble the filter housing.
- Restore circulation, release trapped air, and inspect the filter for leaks.
- Record the clean operating pressure for future maintenance reference.
Always follow Pentair's safety procedures when servicing a pressurized pool filter. Never attempt to open the filter housing while the system is under pressure.
Related Pentair System:3 Filter Cartridges
Need to replace the matching outer cartridge? Aqua Pool Supply also carries the genuine OEM replacement:
- Pentair Sta-Rite System:3 S7M400 Outer Filter Cartridge, 264 Sq Ft | 25022-0224S – Matching outer replacement cartridge for the same S7M400 filtration system.
Restore Your Sta-Rite System:3 Filtration Performance
The Pentair 25021-0223S 136 Sq Ft Inner Replacement Filter Cartridge provides a genuine OEM replacement solution for the Sta-Rite System:3 S7M400 modular media filter. Designed to work with the matching outer cartridge, this replacement module helps maintain effective debris removal, proper water circulation, and dependable swimming pool filtration.
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.
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