Pentair Grid Assembly for FNS Plus 36 | 59023500
Pentair
SKU: 59023500
Pentair FNS Plus 36 Complete D.E. Grid Assembly (Element Cluster) | 59023500
The Pentair 59023500 is a factory replacement complete element grid assembly for 36 sq. ft. vertical-grid D.E. pool filters. This pre-assembled grid cluster replaces the internal grids and manifold/collector assembly to restore proper filtration when your existing grids are torn, cracked, warped, or heavily coated with scale and oils that won’t clean out.
Compatibility
- Fits: Pentair FNS® Plus 36 / FNSP36 vertical grid D.E. filters (where parts diagram specifies 59023500)
- Also used on: select Titan RPM 36 sq. ft. vertical grid D.E. filters (where parts diagram specifies 59023500)
- Tip: Confirm your filter model and square footage (36 sq. ft.) before ordering—grid assemblies are not interchangeable across sizes.
Key Features
- Complete 36 sq. ft. grid set: replaces the entire internal grid pack for consistent filtration performance.
- Pre-assembled cluster: designed to drop in as a complete assembly (reduces install time vs. replacing individual grids).
- Restores water clarity: fresh grid fabric helps capture fine debris when properly charged with D.E.
- Fixes D.E. blowback symptoms: helps correct D.E. returning to the pool caused by torn grid fabric or broken frames (after confirming the air relief and internal seals are in good condition).
What’s Included
- Complete internal grid assembly for 36 sq. ft. FNS Plus-style filters
- Grid count: typically 7 full grids and 1 partial grid (pre-installed in the cluster)
- Manifold/collector components and tie rods as supplied with the complete assembly
Specifications
- Brand: Pentair
- Part Number: 59023500
- Filter Type: D.E. (vertical grid)
- Filtration Area: 36 sq. ft.
- Grid Height: approx. 18" (overall installed height varies slightly by assembly/manifold measurement)
- Quantity: 1 complete grid assembly (cluster)
Common Reasons to Replace
- D.E. powder returning to the pool (torn grid fabric, broken grid frame, or damaged manifold)
- Persistent cloudy water even after proper backwash/cleaning and correct D.E. recharge
- Cracked/brittle grids from age, chemical damage, or freeze conditions
- Major filter rebuild where you want all-new internal filtration surfaces
Installation Notes
- Shut off the pump, relieve pressure at the air relief, and open the filter per manufacturer procedure.
- Remove the old grid assembly, then clean debris from the tank bottom and inspect the standpipe and sealing surfaces.
- Reinstall the new assembly, ensuring it seats fully and aligns correctly before closing the tank.
- After restart, recharge the filter with the correct amount of D.E. for a 36 sq. ft. filter (follow your filter manual for exact dosing).
Related Products
- Search Aqua Pool Supply for 59023500
- Pentair FNS Plus 36 (FNSP36) replacement parts
- D.E. filter powder
- FNS Plus tank O-rings
- D.E. grid cleaner / degreaser
- Silicone lubricant for O-rings (filter-safe)
- Filter air relief assemblies
Maintenance Tips
- Backwash/clean on schedule and recharge with the correct D.E. amount—running undercharged can reduce clarity and increase grid loading.
- Deep-clean grids periodically (degrease, then descale if needed) to prevent oils and minerals from permanently restricting flow.
- Always relieve pressure before opening the filter, and inspect the tank O-ring each time you service the unit.
- Maintain balanced water chemistry to reduce scale buildup that shortens grid life and hurts filtration performance.
Questions about returns? View our return policy.
Hours Of Operation:
Monday - Friday: 8:00 am to 4:00 pm Phoenix Time
Saturday and Sunday: Closed
- Orders costing more than $300 WILL be required to have signature confirmation upon delivery.
- Handling time is typically only 1 day.
- Any item ordered after 1pm Phoenix time, may not ship same-day.
- Call us if you require expedited shipping and we can give you quotes based on your needs.
Return Policy:
- All products, except as noted below, are eligible for return up to 30 days after receipt of item.
- For returns, an RMA form must be filled out HERE or customers can call for additional help.
- Shipping costs will be deducted from all returned items.
- Any item that is missing accessories, original packaging, or is not returned in the same condition that it was received in, may be subject to a re-stocking fee up to 100% based on the condition we receive it in.
- Items broken, damaged, or inoperable due to installer error will not be refunded.
- Fill out the return form or give us a call to obtain an RMA and return shipping label.
- There are no returns on the Pentair Colorsync 618031
- No returns on pool cleaners.
- No returns on opened seals and o-rings.
- No returns on capacitors.
- If a light is returned because it "doesn't work" and it tests fine, the cost to ship and a re-stocking fee will be deducted from the refund.
- All products denied upon arrival at customers house WILL be charged the cost to ship.
- Visa Gift Card Promotions: Gift cards are sent within 14 days of the order. When accepting the Visa Gift card, you agree that if your order is returned or refunded, this amount will be deducted from the refunded amount. All Visa Gift cards are sent via email in an E-Gift Card format and are non refundable.
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