This is the genuine OEM cover nut for the Pentair UltraFlow Plus pool pump strainer housing. It secures the strainer pot cover (lid) against the pump body, maintaining a watertight seal so the pump holds prime and operates at rated flow. Without a serviceable nut in place, the cover cannot be correctly torqued, the seal fails, and the pump loses suction.<\/p>\n
The cover nut draws and holds the strainer lid firmly onto the pump pot, compressing the lid O-ring against the housing seat. Correct clamping torque is the difference between a pump that holds prime reliably and one that air-locks on every start. It also acts as the single mechanical point of access for routine basket inspection \u2014 you remove it every time you clear debris from the strainer basket.<\/p>\n
This nut is supplied as a genuine Pentair spare for the UltraFlow Plus pump family. Verify your pump model against the part number R39105000 before ordering, as lid hardware can vary across UltraFlow generations. If in doubt, cross-reference against the exploded parts diagram for your specific pump.<\/p>\n
Corrosion pitting, rounded flats, or a cracked thread profile are the most common failure modes. If you’re fighting to seat the cover properly, or the nut spins without generating clamping force, the thread is worn and replacement is overdue. A damaged nut also risks cross-threading and cracking the strainer pot lid during reassembly.<\/p>\n
Switch off and isolate the pump at the breaker before you start. Unscrew the old nut by hand or with the correct-size spanner, lift the strainer lid clear, clear the basket, inspect the lid O-ring, then refit in reverse order. Hand-tighten the new nut first to confirm thread engagement, then snug with a spanner \u2014 do not overtighten, which can crack the lid or distort the O-ring seat.<\/p>","protected":false},"excerpt":{"rendered":"