Pool Filter Parts: Names, Functions, and Replacement Costs

Every pool filter, whether sand, cartridge, or DE, is a pressure vessel with a handful of parts inside. Knowing what those parts are called is more useful than it sounds: when the filter leaks, blows sand into the pool, or lets debris through, the fix is almost always one specific part, and you cannot order it or ask about it without the right name. This guide names every part on all three filter types, explains what each one does, flags the parts that wear out, and gives typical replacement costs so you know whether a repair makes sense.

If you already know a part has failed and want the fix itself, the pool filter repair guide covers the actual procedures. This page is the parts map.

Parts Every Pool Filter Shares

These parts appear on sand, cartridge, and DE filters alike, so learn them first.

• Tank body - the pressure vessel itself, usually fiberglass reinforced plastic or thermoplastic. It holds the filter media and takes 20 to 40 psi of working pressure. Tanks rarely fail, but a cracked tank is the one part failure that usually means replacing the whole filter.
• Pressure gauge - the small dial on top of the tank or valve that reads system pressure in psi. It is your only window into filter condition: rising pressure means dirty media, low pressure means a flow restriction before the filter. Gauges are cheap and fail often, so if yours reads zero or never moves, test it before assuming a bigger problem. The guide on a pool filter pressure gauge not working walks through that diagnosis.
• Air relief valve - the small twist valve next to the gauge that bleeds trapped air from the tank after you reopen the system. Trapped air compresses under pressure and is dangerous, which is why you open this valve every time you restart the pump after service.
• Drain plug or drain cap - a threaded plug at the bottom of the tank for draining water before winterizing or service. Its tiny o-ring is a classic slow leak source.
• Clamp band or lid ring - on two piece tanks, the band or threaded ring that holds the halves or lid together against pressure. Never loosen it while the pump is running.
• Tank o-ring - the large rubber ring that seals the tank halves or lid. When it dries out or flattens, the filter weeps water at the seam. Lubricate it with silicone lube once or twice a season and it lasts years longer.
• Unions - the threaded fittings connecting the filter to the plumbing. Each union has its own o-ring, and a drip at a union is almost always that o-ring, not the pipe.

Sand Filter Parts

Sand filters have the most named parts because the valve does so much work.

• Multiport valve - the multi position valve mounted on top or on the side of the tank that routes water for filter, backwash, rinse, waste, recirculate, and closed modes. Inside it are three parts that matter: the spider gasket (the flat rubber gasket with spokes that seals each port), the rotor or diverter (the rotating piece the handle turns), and the handle with its spring and pin. A worn spider gasket is the number one cause of water trickling out the backwash line during normal filtering. The full breakdown of failure modes is in pool filter multiport valve problems.
• Standpipe - the vertical pipe running down the center of the tank from the valve to the laterals. Water returns to the pool through it.
• Laterals - the finger shaped screens that radiate from the bottom of the standpipe like spokes, buried under the sand. Their slots let water through but hold sand back. A single cracked lateral sends sand into the pool through the return jets, and replacing one means scooping out all the sand. A pool filter laterals search on Amazon covers most Hayward and Pentair sizes, but match your exact model number before ordering.
• Sight glass - the small clear window on the valve’s waste port that shows backwash water. You backwash until it runs clear.
• Sand media - the 50 to 300 lb of pool grade silica sand inside the tank. It is a consumable with a 5 to 7 year life; the procedure is covered in how to change pool filter sand.

Cartridge Filter Parts

Cartridge filters are the simplest internally, which is part of their appeal.

• Cartridge element - the replaceable pleated filter itself, made of three pieces bonded together: the pleats (spun polyester fabric folded to pack 100 to 500 square feet of surface into a small cylinder), the end caps (the plastic tops and bottoms that seal the pleats and seat the cartridge in the housing), and the inner core (the rigid perforated tube that keeps the pleats from collapsing inward under pressure). Cartridges are consumables; when to replace a pool filter cartridge covers the signs that cleaning is no longer enough.
• Locking ring - the large threaded ring or clamp that secures the filter lid over the cartridge. Hand tight plus the manufacturer’s stated torque, never a cheater bar.
• Manifold - on large multi cartridge units (four cartridges is common), the plastic assembly at the top that holds all the cartridges in position and collects the filtered water. A cracked manifold lets unfiltered water bypass straight to the pool, and it is the part to check when water stays cloudy despite clean cartridges.

DE Filter Parts

DE filters look like cartridge filters outside but are different inside.

• Grid assembly - the complete internal skeleton: a top and bottom manifold holding a set of curved grids (usually eight, one shorter than the rest to clear the standpipe) covered in filtration fabric. The DE powder coats this fabric and does the actual filtering.
• Individual grids or fingers - grids can be replaced one at a time, which matters because a single torn grid returns DE powder to the pool as a gray cloud at the jets. Bump style filters use fabric fingers instead of curved grids, but the job is identical. Inspection and replacement are covered in the DE pool filter grids guide.
• Bump handle - on bump style filters (Hayward Perflex is the common one), the external handle you pump to knock spent DE cake off the fingers so it redistributes, extending time between full cleanings.
• DE powder - the diatomaceous earth itself, a consumable. You add a measured amount through the skimmer after every backwash or teardown. It is not optional; running a DE filter with bare grids clogs the fabric quickly.

Which Parts Wear Out and What They Cost

Rubber wears fastest, plastic next, and the tank itself essentially never. Typical lifespans and prices:

Two cheap upgrades prevent most surprise failures. A pool filter o-ring kit on Amazon matched to your filter model replaces every seal at once for less than 20 dollars, which is easier than chasing one drip at a time. And since gauges fail so quietly, keeping a spare pool filter pressure gauge on the shelf means you can swap and compare readings in two minutes instead of guessing.

How to Find the Right Part

Parts are model specific, and models that look identical from five feet away use different laterals, gaskets, and cartridges. The reliable process:

1. Read the tank label. Every filter has a plate or sticker on the tank body with the manufacturer and model number, for example Hayward S210T or Pentair Clean and Clear Plus 320. That model number is your search term.
2. Pull up the exploded parts diagram. Manufacturers publish exploded diagrams in the manual and on their websites, with every part numbered. Search the model number plus “parts diagram” and you will find a labeled drawing that removes all guesswork about which piece you are holding.
3. Decide OEM or generic honestly. For o-rings, gauges, drain plugs, and sight glasses, generic parts are fine and cost half as much. For laterals, spider gaskets, cartridges, and grids, dimensions matter down to the millimeter, so buy OEM or a compatible brand with strong reviews for your exact model. A generic cartridge that is a quarter inch short will bypass around the end caps forever.

Where to Buy Pool Filter Parts

Amazon carries nearly everything: search your model number plus the part name, for example “S244T lateral” or “CCP320 cartridge”, and cross check the listed compatible models before ordering. For odd sized o-rings that come up as unavailable or bundled into expensive kits, a local pool store is often faster; bring the old o-ring and they will match it off a sizing board in minutes. For obscure parts on older filters, the manufacturer’s own parts site or a dedicated pool parts retailer will have the part number from the exploded diagram even when general retailers do not.

The pattern worth remembering: most filter problems trace to a part that costs less than 30 dollars. Name it correctly, match it to your model number, and the repair is usually a 20 minute job.

Related Guides

• Pool Filter Repair - fixing leaks, cracks, and failed parts once you know which part it is
• Pool Filter Multiport Valve Problems - spider gasket, rotor, and handle failures explained
• Pool Filter Pressure Gauge Not Working - testing and replacing a stuck or dead gauge
• When to Replace a Pool Filter Cartridge - signs a cartridge is past cleaning
• DE Pool Filter Grids - inspecting and replacing torn grids
• How to Change Pool Filter Sand - full sand replacement including lateral inspection