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Pentair

Pentair FNS Plus Tank Lid Assembly 48 sf 170021

Pentair FNS Plus Tank Lid Assembly 48 sf 170021

$333.99 USD
$333.99 USD
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Shipping calculated at checkout.

The Pentair FNS Plus Tank Lid Assembly 170021 restores a pressure-tight seal so your filtration system runs safely. Designed specifically for the 48 sq ft FNS Plus filter, this genuine OEM lid assembly protects internal components and keeps your pool water crystal clear. When pressure integrity matters, this is the replacement professionals trust.

What happens if my Pentair FNS Plus filter lid is damaged or leaking?

A compromised lid can cause air leaks, pressure loss, and unsafe operating conditions in your DE filter system. The Pentair 170021 Tank Lid Assembly replaces worn or cracked covers with an exact-fit OEM solution built for the 48 sq ft FNS Plus model. When installed correctly, it restores proper sealing, maintains system pressure, and helps extend the life of your filter grids and internal components.

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Key Features

  • Genuine Pentair OEM tank lid assembly
  • Designed specifically for FNS Plus 48 sq ft DE filters
  • Heavy-duty, chemical-resistant construction
  • Maintains proper tank pressure and filtration performance
  • Direct replacement for cracked, warped, or aging lids

Technical Specifications

  • Part Number: 170021
  • Compatible Model: Pentair FNS Plus 48 sq ft DE Filter
  • Filter Type: Diatomaceous Earth (DE)
  • Material: UV- and chemical-resistant polymer
  • Includes: Tank lid assembly only (o-ring and clamp band sold separately unless otherwise noted)

Specs

Best For: Ideal Pool Types & Conditions

Best for residential pools using the Pentair FNS Plus 48 sq ft DE filter system. This lid assembly is ideal when your original cover shows cracks, warping, or signs of pressure stress after years of sun exposure and chemical contact. A secure lid is critical for DE systems, where internal pressure and proper sealing directly affect filtration performance.

Best for:
Pools equipped with Pentair FNS Plus 48 sq ft filters
Homeowners performing DE grid cleaning or seasonal maintenance
Systems experiencing minor air leaks from a worn lid

Not ideal for:
FNS Plus models with different square footage (36, 60, etc.)
Cartridge or sand filter systems

Our Expert Verdict: Real-World Results

In real-world pool service conditions, a solid tank lid is non-negotiable for safe DE filter operation. The Pentair FNS Plus 170021 Tank Lid Assembly delivers the structural integrity and exact fit professionals rely on during routine maintenance and rebuilds. Once installed, you’ll notice consistent pressure readings and improved system reliability.

If you want dependable OEM performance without guesswork, ShastaPoolSupply.com delivers genuine Pentair parts with fast shipping and knowledgeable support. We help you choose the right replacement the first time — so your pool stays clean, clear, and running strong.
Dan Shasta Pool Supply Expert

Expert Comparison & Pro Tips

Aftermarket lids may appear similar, but they often lack the precision fit required for proper band clamp alignment and safe pressure sealing. The Pentair 170021 is molded to match the 48 sq ft FNS Plus tank body exactly, reducing the risk of uneven compression or sealing issues. In field service, mismatched lids are a common cause of persistent air leaks and fluctuating pressure readings.

Pro Tip: Always inspect and lubricate the tank o-ring when replacing the lid. Even a brand-new lid can leak if paired with a dry or flattened o-ring. Replacing both at the same time often prevents repeat service calls.

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What our customers are saying

Product knowledge by Zack was spot on. Shipping was surprisingly fast, Price matching is a plus. Thanks

Kenneth S

Straight forward buy with all the parts needed for the job. It's better buying directly from experts than messing with Amazon

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Shasta has been and will always be a superior Swimming Pool Supply and construction to that exceeds performance. Great Service on All Levels.

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