Product Overview

The Pentair FNS® Plus 48 Sq. Ft. D.E. Filter (EC-180008) is a high-performance vertical-grid filtration system designed to deliver exceptionally clear water for residential swimming pools and pool-and-spa combinations. Its 48 square feet of effective filtration area uses diatomaceous earth-coated grids to capture extremely fine dirt, algae and suspended particles.

The FNS Plus filter features curved vertical grids that maximize filtration surface area while helping minimize internal flow restriction. Its fiberglass-reinforced polypropylene tank provides dependable strength, chemical resistance and corrosion protection for long-term outdoor operation.

Pentair identifies the EC-180008 as the e-commerce version of the FNSP48 filter. The complete internal grid assembly is included, but a compatible backwash valve and D.E. filter media must be purchased separately. Pentair’s current product listing rates the FNSP48 at 96 GPM.

Key Features

• 48 sq. ft. effective filtration area
• Vertical-grid D.E. filtration design
• Rated flow of approximately 96 GPM
• Captures particles as small as approximately 5 microns
• Complete internal grid assembly included
• Curved grids maximize available filtration area
• Top-to-bottom backwashing
• Fiberglass-reinforced polypropylene tank
• Chemical- and corrosion-resistant construction
• High Flow™ manual air-relief valve
• Continuous internal air-relief system
• Easily removable grid pack
• Conveniently positioned drain for cleanout
• 2-inch plumbing connections
• Maximum continuous operating pressure of 50 PSI
• Maximum internal water temperature of 104°F
• E-commerce model

Pentair describes the FNS Plus as a vertical-grid D.E. filter with curved grids, an easily removable grid pack, a High Flow manual air-relief valve and a chemical-resistant tank.

Specifications

Pentair’s published FNS Plus brochure lists the FNSP48 with a 48 sq. ft. filtration area, 21.5-inch diameter, 74-inch vertical clearance and turnover capacities of 46,080, 57,600 and 69,120 gallons over eight, ten and twelve hours.

D.E. Media Requirement

The FNSP48 requires approximately 4.8 pounds of diatomaceous earth when coating clean filter grids. D.E. must be introduced through the pool skimmer after the system has started and all trapped air has been safely released.

Pentair specifies a full D.E. charge of 4.8 lbs. for the FNSP48.

Only swimming-pool-grade D.E. should be used. Follow all handling instructions and wear appropriate respiratory and eye protection when working with dry D.E. powder.

Grid Assembly

The FNSP48 uses a complete removable vertical-grid assembly consisting of:

• Seven full-size grids
• One partial grid
• Top manifold
• Internal air-bleed assembly
• Grid locator
• Tie rod and retaining hardware
• Outlet standpipe

Pentair identifies 59023400 as the complete replacement grid assembly for the 48 sq. ft. FNS Plus filter. Individual replacement grids include seven 59002400 full grids and one 59002300 partial grid.

Ideal For

• Residential in-ground swimming pools
• Large residential pools
• Pool-and-spa combinations
• New pool construction
• Equipment-pad renovations
• Applications requiring very fine filtration
• Pools prone to fine dust, pollen or algae
• Systems operating at flow rates up to approximately 96 GPM
• Pool owners seeking maximum water clarity

Benefits

• D.E. filtration captures particles smaller than typical sand or cartridge filters
• Helps produce exceptionally clear, polished pool water
• Large 48 sq. ft. grid area provides high dirt-holding capacity
• Curved grids maximize usable filtration surface
• Internal design helps reduce flow restriction
• Removable grid pack simplifies deep cleaning
• Durable tank resists corrosion and pool chemicals
• Top-to-bottom backwashing helps remove accumulated debris
• High Flow air relief supports efficient filtration
• Compatible with standard slide or multiport backwash valves

What’s Included

• Pentair FNS Plus FNSP48 filter tank
• Complete 48 sq. ft. internal grid assembly
• Seven full-size filter grids
• One partial filter grid
• Top manifold
• Internal air-bleed assembly
• Tank clamp assembly
• High Flow™ manual air-relief valve
• Pressure gauge
• Drain plug
• Installation and operating documentation

A backwash valve, D.E. powder, plumbing unions, pipes, fittings and installation materials are not included unless specifically stated by the seller.

Valve Compatibility

The EC-180008 requires a compatible valve for normal filtration and backwashing. Depending on the installation, the filter may be used with:

• Pentair slide valve
• Pentair multiport valve
• Compatible 2-inch D.E. backwash valve
• Separation tank system where required by local code

The valve must be specifically designed for D.E. filtration and must match the filter’s port spacing and plumbing configuration.

Filter Maintenance

The filter should be backwashed when the pressure increases above the recorded clean-filter starting pressure or when circulation decreases. After backwashing, the grids must be recoated with the correct amount of fresh D.E.

Periodic manual cleaning is also required. The grid assembly should be removed and rinsed when:

• Pressure remains high after backwashing
• Water flow does not return to normal
• The filter is being winterized
• Grids show heavy scale or oil accumulation
• The system has experienced an algae outbreak

Inspect the grids for tears, separated seams, cracked frames or damaged manifold components during each manual cleaning.

Installation Requirements

Install the filter on a solid, level equipment pad with adequate space for plumbing, valve operation and future servicing.

The FNSP48 requires approximately 74 inches of vertical clearance so the upper tank section and grid assembly can be safely removed.

The plumbing system must be mechanically supported so pipe weight does not place strain on the filter or valve. A suitable waste line or D.E. separation tank must be installed in accordance with applicable local codes.

The filter must be installed and serviced by a qualified pool professional. Trapped air inside a pressurized filter can cause the lid to separate with extreme force. Always shut off power, prevent automatic pump restart, open the air-relief valve and confirm the pressure gauge reads zero before servicing.

Confirm Before Ordering

Please verify:

• The required model is FNS Plus FNSP48
• The correct SKU is EC-180008
• A 48 sq. ft. D.E. filter is appropriate for the pool
• System flow does not exceed the filter’s published rating
• Approximately 74 inches of vertical clearance is available
• The equipment pad can accommodate a filter approximately 21.5 inches in diameter
• Existing plumbing is compatible with 2-inch connections
• A compatible backwash valve is installed or will be purchased separately
• Approximately 4.8 lbs. of pool-grade D.E. is available for initial coating
• Local regulations allow D.E. backwash discharge or require a separation tank
• The complete internal grid assembly is included

Warranty Information

The EC-180008 is an e-commerce-designated Pentair product and is covered by Pentair’s applicable limited warranty when purchased, installed and operated according to Pentair’s current warranty requirements.

Warranty eligibility may depend on the seller, installation method and installer qualifications. Damage caused by improper installation, operation without D.E., excessive pressure, freeze damage, chemical misuse or failure to follow required service procedures may not be covered.

Professional installation by a qualified pool professional is strongly recommended.