Should You Install a Filter on a Lake-Fed Sprinkler System?

It Depends on the Debris Type

• Mud, silt, algae: A filter will clog rapidly. Better to relocate the pump suction intake higher in the water column or add a floating intake screen.
• Sand, grit, shell fragments: A quality centrifugal sand separator or screen filter (30–60 mesh) installed just downstream of the pump can dramatically extend rotor life.

Filter Placement and Sizing

Install the filter after the pump but before the first valve. Size it for the maximum system flow (GPM) with a pressure drop under 5 psi at peak flow. A 1-1/2″ or 2″ filter with a flush valve simplifies maintenance.

Why Rotors Fail Year After Year

Rotors stop rotating when grit wears the turbine or gear drive. Even a small amount of abrasive particles in lake water will destroy 3–4 rotors per season. A filter is worthwhile if the debris is particulate.

Aging Pump Cycling On/Off

Your 1-1/2 HP pump runs 40–50 minutes, then cycles 10 on/10 off. Two likely causes:

1. Motor wear: Worn bearings or windings increase heat, triggering the thermal overload.
2. Voltage drop from longer wire run: Moving the pump farther from the panel increases resistance. Measure voltage at the motor terminals while running; if it’s below 210 V (on 230 V), upsize the wire.

Recommended Action

1. Test voltage at the motor under load.
2. If voltage is good, plan for pump replacement—the motor is likely near end of life.
3. If voltage is low, run larger gauge wire (or a second parallel feed) before replacing the pump.