Pentair Quad DE Filter Guide: Cleaning, Backwashing, and Troubleshooting

The Pentair Quad DE is a cartridge-style diatomaceous earth filter available in three sizes (60, 80, and 100 square feet). Unlike the FNS Plus, which uses fabric grids, the Quad DE uses cylindrical filter cartridges pre-coated with D.E. The filter can be backwashed for routine maintenance, and cartridges can be manually cleaned when backwashing is no longer sufficient. This guide covers DE amounts, backwashing, cartridge cleaning, clamp specifications, winterizing, and troubleshooting.

Filter Overview

The Quad DE operates at a maximum working pressure of 50 psi. It must never be operated for more than 3 minutes without a D.E. coating — this will damage the cartridges. The Quad DE uses a different flow pattern than other Pentair D.E. filters; if replacing a filter or valve, verify the flow pattern before permanently installing.

Record the original starting pressure when the system is first commissioned. Backwash or service the cartridges when pressure reads approximately 10 psi above the original starting pressure, or when significant flow reduction is noticed. For variable speed pumps, record the original starting pressure and pump RPM together.

Compatible Valves

The Quad DE has a unique flow pattern. Compatible Pentair valves include:

• P/N 261055 — 2" Multiport Valve
• P/N 261173 — 1-1/2" Multiport Valve
• P/N 261050 — 2" HiFlow Valve
• P/N 263064 — 2" PVC Slide Valve

Coating Cartridges with Diatomaceous Earth

1. Mix the required amount of D.E. (see table above) with sufficient water in a bucket.
2. If using a Slide Valve: twist the handle to unlock, raise to the full up position, and lock in place. If using a Multiport Valve: set to FILTER or VACUUM TO POOL position.
3. Follow the Startup Instructions below to start the pump.
4. With the pump running and the skimmer valve open, pour the D.E. slurry directly into the skimmer. The pump will draw it through the filter.
5. Record the original starting pressure and original pump RPM (if variable speed).

Disassembling the Filter (Opening)

1. Disconnect power to the pump and any automatic controls at the circuit breaker.
2. Open the filter air relief valve: turn the top 1/4 turn counterclockwise until it snaps into the OPEN position.
3. Stand clear of the filter and wait until all pressure is relieved. Pressure gauge must read zero (0) psi.
4. Close suction and return lines.
5. Remove the drain plug from the bottom of the filter and allow the tank to drain.
6. While holding the clamp ends together, use a 3/4-inch socket and wrench to remove the clamp nut counterclockwise. Hold the clamp halves securely while removing the nut to prevent the decompressed clamp from sliding off and damaging plumbing.
7. Remove the clamp ring and set aside.
8. Carefully remove the filter lid. Do not lift the lid by the air relief valve — this may damage the valve. If the lid is tightly sealed, shift it gently side to side to break the seal. Do not use tools to break the seal.
9. Set the filter lid and tank O-ring aside in a safe place.

Reassembling the Filter (Closing)

1. Verify power to the pump and automatic controls is disconnected at the circuit breaker.
2. Ensure the tank O-ring is clean and undamaged. Seat it along the flange of the filter base.
3. Place the filter lid onto the filter base. Verify the O-ring is not pinched between the lid and base. Do not lift the lid by the air relief valve.
4. Position the clamp ring over both the upper and lower tank flanges, then bring the ends together.
5. Using Tongue-and-Groove Pliers, compress the clamp. While holding, start the clamp nut by hand.
6. Using a 3/4-inch socket and wrench, tighten the clamp nut to 16–18 ft-lbs (22–24 Nm).
7. Verify the gap between the ends of the clamp is between 1/2-inch and 3/4-inch (13–19 mm).
8. Reinstall the drain plug.
9. Follow the Startup Instructions below.

Startup Instructions

1. Before starting the pump, confirm:
   • Gap between clamp ends is between 1/2-inch and 3/4-inch (13–19 mm)
   • Filter air relief valve is open (1/4 turn CCW to open)
   • Suction and return lines are open
2. Reestablish power to the pump at the circuit breaker.
3. Stand clear of the filter, then start the pump.
4. Verify proper operation. The system is not operating correctly if:
   • A solid stream of water does not appear from the valve within approximately 30 seconds of pump prime
   • Water leaks from under the clamp
   • Pressure gauge indicates pressure before water flows
   If any of these conditions exist, immediately disconnect power to the pump and automatic controls. Never attempt to adjust the clamp while the pump is receiving power.
5. After confirming proper operation, turn the air relief valve 1/4 turn clockwise until it snaps into the CLOSED position.

Backwashing the Filter (Without Separation Tank)

Backwash when pressure reads approximately 10 psi above the original starting pressure, or when significant flow reduction is noticed.

1. Shut off power to the pump and automatic controls at the circuit breaker. Open the air relief valve and wait until gauge reads zero.
2. Place the skimmer valve in the full OPEN position and close the main drain line.
3. Remove the pump lid, clean the strainer basket, reinstall basket and lid.
4. For a Slide Valve: push the handle down and lock. For a Multiport Valve: place in BACKWASH position.
5. Open the filter air relief valve. Stand clear, then start the pump.
6. After a steady stream of water appears, close the air relief valve.
7. When water from the discharge/waste line runs clear, shut off the pump.
8. Return the valve to the FILTER position.
9. Follow Startup Instructions above.
10. Add the required amount of D.E. per the Coating Cartridges procedure above.

Backwashing the Filter (With Separation Tank)

The separation tank captures spent D.E. waste for disposal rather than sending it to drain. Ensure the separation tank air relief valve and clamp are maintained per the separation tank manual.

1. Shut off pump and relieve pressure (same as above, steps 1–3).
2. For a Slide Valve: push handle down and lock. For a Multiport Valve: place in BACKWASH position.
3. Open both the filter and separation tank air relief valves. Stand clear, then start the pump.
4. After a steady stream of water appears, close both air relief valves.
5. When water from the discharge/waste line runs clear, shut off the pump.
6. Open the separation tank air relief valve and wait for water to stop draining.
7. Open the separation tank per its manual. Empty the separation bag and dispose of spent D.E. per local codes and ordinances.
8. Reinstall the bag, tank lid, and clamp per the separation tank manual.
9. Return the valve to FILTER position. Follow Startup Instructions above. Add D.E.

Manually Cleaning the Cartridges

Manual cleaning is required when pressure remains high after backwashing, or when winterizing the filter.

1. Follow Disassembling the Filter above.
2. Remove the Compression Spring/Adapter from the Top Manifold.
3. Remove the Top Manifold from the filter cartridges and lay it aside.
4. Carefully remove each cartridge.
5. Using a garden hose with a straight-flow nozzle, hold at a 45-degree angle and wash each cartridge from top to bottom. Pay close attention to the area between pleats.
6. Wash the inside of the filter tank and bottom manifold. Water and debris will drain through the drain plug.
7. Inspect the O-ring around the filter flange — it must be clean and evenly seated.
8. Reinstall the bottom manifold, cartridges, and top manifold, ensuring the spring and standpipe assembly are retained on the top manifold.
9. Follow Reassembling the Filter and Startup Instructions above.
10. Add D.E. per the Coating Cartridges procedure above.

Maintaining the Pressure Gauge

Replace the pressure gauge (P/N 190058z) if any of the following conditions exist:

• Gauge does not read zero (0) psi when pressure is relieved and system is off
• Gauge does not read correctly while the system is operating
• Gauge is difficult to read or is damaged

Cleaning the Air Relief Valve

1. Shut off power to the pump and automatic controls at the circuit breaker. Open the air relief valve and wait until all pressure is relieved (gauge reads zero).
2. With the valve installed, pull out the locking tabs and remove the valve stem and cover assembly counterclockwise.
3. Pull the stem and cover away from the valve body.
4. Remove any debris. Insert a 5/16-inch drill bit through the valve body to verify the air passage is open.
5. Check that the O-rings are in good condition, properly positioned, and lubricated with a silicone-based lubricant. Do not use petroleum-based products.
6. Reinstall the valve stem and cover by pressing downward and turning clockwise until it snaps into position.

Winterizing

1. Follow Disassembling the Filter above.
2. Follow the Manually Cleaning Cartridges procedure above.
3. Store the cartridges and drain plug in a location protected from freezing conditions.
4. Follow Reassembling the Filter above.

Troubleshooting

Replacement Part Numbers

Note on clamps: Spring clamp kits (Item 8b, P/N 190003) are only compatible with Quad DE filters manufactured before August 2025. Filters manufactured August 2025 and later use the cast clamp assembly (P/N 198102).