Hayward Perflex DE Filter: How the Bump Mechanism Works and How to Rebuild It

Hayward's Perflex line is one of the few DE filters on the market that regenerates its filter cake without a backwash valve. That convenience depends on a small set of moving parts — the bump handle, the bump shaft, and the diaphragm gasket that seals the shaft where it enters the filter head. When those parts wear, the filter starts leaking, loses its ability to regenerate, and service calls follow. This guide explains how the mechanism works, what wear looks like in the field, and how to rebuild it.

How the bump mechanism works

A Perflex filter holds a nest of flexible tubes coated with a cake of DE powder. Dirt collects on the outside of that cake as water passes through. Instead of backwashing, the operator strokes the bump handle up and down. The handle drives the bump shaft, which lifts and drops the entire tube nest inside the tank. The sudden motion flexes the tubes and knocks the DE cake — dirt and all — off the tube surfaces. When the pump restarts, the mixture redeposits on the tubes as a fresh, porous cake, and filtration pressure drops back toward its clean baseline.

The clever part of the design is also its weak point. The bump shaft has to pass through the pressurized filter head while still being free to move. A flexible diaphragm gasket seals that penetration. Every bump cycle flexes the gasket; sun, chlorinated water, and time harden it. Eventually it cracks, and the filter starts weeping around the handle. The shaft itself also wears where it rides in the head, and a worn shaft chews through replacement gaskets quickly if it is not replaced at the same time — which is why the service kits pair the two.

Field symptoms of a worn diaphragm gasket or bump shaft

Watch for these complaints on a Perflex system:

• Water leaking around the bump handle or filter head while the pump runs. This is the classic sign of a cracked diaphragm gasket. It often starts as a slow weep that only shows as a wet spot or calcium trail on the tank.
• Spraying or steady dripping during the bump stroke. The gasket may seal at rest but open up when the shaft moves — flexing exposes the crack.
• A loose, sloppy, or gritty-feeling handle. Play in the handle usually means the shaft or its wear surfaces are gone, not just the gasket.
• Pressure that will not drop after bumping. If a full set of bump strokes no longer brings gauge pressure back down, the nest may not be moving through its full travel. A worn or broken shaft assembly is one cause; a tube nest overloaded with old DE and oils is another.
• Shortening cycles between DE changes. Perflex filters still need periodic full cleanouts. If regeneration barely buys any run time, inspect the whole bump assembly and the tube nest while the filter is open.

None of these symptoms fix themselves, and a leaking head penetration only gets worse under pressure. Plan the rebuild at the next DE change so you only open the filter once.

Rebuild procedure

Before you open anything

Shut off power to the pump at the breaker — not just the timer — so it cannot start while the filter is open. Open the filter's air relief and let the tank bleed to zero pressure, then open the drain so the tank empties below the head. Never loosen a filter head or clamp with pressure in the tank.

Step-by-step

1. Remove the bump handle hardware. Note the orientation of every washer and spacer as it comes off; taking a phone photo first saves guesswork on reassembly.
2. Open the filter head per the model's service manual and lift it clear. This is the right time to hose down the tube nest and inspect the tubes for tears or hardened cake.
3. Withdraw the bump shaft from the head and slide off the old diaphragm gasket. Inspect the shaft's sealing and wear surfaces. If you can feel a ridge or see polishing and scoring, replace the shaft with the kit rather than reusing it.
4. Clean the gasket seat in the head. Old gasket material and scale must come off completely or the new seal will weep from day one.
5. Install the new diaphragm gasket and shaft from the kit, along with the new O-ring where the kit includes one. Lubricate rubber parts with a pool-safe silicone lubricant only — never petroleum grease, which swells and softens rubber.
6. Reassemble the head, seat its sealing surfaces evenly, and refit the handle hardware in the order you photographed.
7. Refill and recharge. Close the drain, restart the pump, bleed air through the relief until water sprays steadily, then add fresh DE per the filter's labeled capacity through the skimmer.
8. Check for leaks at the handle at rest and while bumping. A correctly seated diaphragm gasket runs dry through the full stroke.

Parts cross-reference

POOLPOINT manufactures aftermarket bump-assembly service kits that replace the Hayward OEM numbers below. Both kits pair the diaphragm gasket with the shaft components so the wear parts are replaced together.

Confirm the filter model from its data plate before ordering: the ECX1105 kit serves the EC65/EC75 family, while ECX5000G covers the other Perflex bump assemblies listed above.

Rebuild the assembly, or replace the filter?

A bump-assembly rebuild is cheap insurance on a tank that is otherwise sound. Replace rather than rebuild when the tank shows structural problems — spider cracking, bulging, or fittings that have gone chalky and brittle — or when the tube nest itself is torn up, since a nest can cost a large share of a new filter. For everything short of that, a gasket-and-shaft kit plus a fresh DE charge restores the bump action for a fraction of replacement cost, and the job fits inside a routine seasonal cleanout.

Sourcing

POOLPOINT manufactures these Perflex-compatible service kits factory direct for US distributors, service companies, and online sellers, with MOQ from 50 pcs per SKU and private label available. If you stock DE filter parts, request a quote for wholesale pricing on ECX5000G and ECX1105.